BLUSHING

Does the coating film look milky on the surface?

SOLUTION

There are generally two possible methods for dealing with this problem on a coated surface.
If the bloom is very noticeable, you will need to sand the dried film back to the raw substrate with 80 grit sandpaper and apply a new coating system starting from the first coat.
Alternatively, in less critical cases, sand out the defect completely using 320 grit sandpaper and recoat.
If the bloom is not particularly noticeable, you can apply a very high-opacity topcoat to hide the blotches areas.
Anyway, before recoating, you will need to identify and fix the cause of the problem.
Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

Humidity is absorbed during drying (solvent-based products).

Change the solvent for a slower type, add small percentages of retarder or non-blushing thinner XS0007/00.
In winter, in northern countries (highly humid), it’s advisable to work with a temperature no lower than 20°C.

Unsuitable or low-quality thinner used.

Change thinner, also taking into account the application conditions (see relevant technical data sheet).

Water coming out of the compressor (solvent-based products).

Use an appropriate air filter system on the compressor. Check the compressor at regular intervals and empty the oil water separator.

Coating film partially touching from the substrate (see also ADHESION problems).

Make sure sanding is carried out evenly over the whole surface to be coated. Always use coating types that are compatible with each other. Avoid stratification of the different coats and use suitable sealers where necessary.
Note: in this particular case, there is no alternative to remove the coating layer completely down from the substrate and then reapply the coating system starting from the first coat once you’ve identified and fix the causes of the problem.

Coatings applied to wood that isn’t completely dry (solvent-based products).

Wait until the substrate is completely dry and there is no condensation on the surface.
Note: in this particular case, there is no alternative but to remove the coating layer completely down from the substrate and then reapply the coating system starting from the first coat once you’ve identified and fix the causes of the problem.

Coating internally incompatible with external agents.

Identify and eliminate the cause of the line contamination (for example, don’t use coatings containing oil or soluble dyes in polyurethane, acrylic, polyester or UV coating systems).
Only use those components given on the product’s technical data sheet.

Basecoat sanded and polished before it has had time to dry completely.

Allow the basecoat to dry for the correct length of time: refer to the technical data sheet.

Water-soluble adhesive (water-based products).

Make sure the adhesives used are water resistant (class D3 or D4).

BUBBLES OF AIR RELEASED FROM PORES

Are air bubbles becoming trapped within the coating film?

SOLUTION

The only way to eliminate the problem of air bubbles appearing on the coated surface is to sand the dried film back to the raw substrate with 80 grit sandpaper and apply a new coating system cycle starting from the first coat, given that it’s practically impossible to fix the problem with persistent sanding and/or additional coats. Anyway, before recoating, you will need to identify and deal with the cause of the problem. Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

Coating viscosity too high.

Increase the amount of thinner used to lower the coating’s viscosity and thus encourage its penetration into the pore and the releasing of the air inside.

Substrate temperature too high (generally with UV systems).

Wait an appropriate amount of time before applying the coating on the substrate to give it time to cool or adjust the UV system’s parameters as required (airflow or line speed).

Product not suitable for application on porous woods.

The nature of the products (for instance, most finishes contain silicones) can cause air to be released from the pore in the event that they come into contact with the bare substrate (for instance, if the pore has not been wetted by the basecoat).
Use a suitable product as a basecoat on the wood to be coated (e.g. base-topcoats or primers with high wetting power) and/or use a suitable sealer.

BUBBLING

Are there bubbles trapped in the coating film?

Note: bubbles trapped in the basecoat can also appear as tiny holes in the surface (see PINHOLES). During sanding, small hollow craters actually open up and, being hard to level out, show through on subsequent coats.

SOLUTION

The only way to eliminate the problem of bubbles on the coated surface is to sand the dried film back to the raw substrate with 80 grit sandpaper and apply a new coating system starting from the first coat.
Alternatively, in less critical cases, sand out the defect completely using 320 grit sandpaper and recoat. Anycase, before recoating, you will need to identify and fix the cause of the problem. Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

Incorrect mixing process: too much curing agent or accelerator (polyesters).

Make sure you mix the coating’s parts correctly and in the right proportions. It’s always best to use scales rather than mixing by volume.

Coating viscosity too high

If the viscosity is too high, it can impede the release of air incorporated into the film during application. When using conventional spray guns with cups, do not apply products with an higher viscosity than 20 seconds measured with a DIN 4 cup. Do not apply excessive amounts of product in a single coat to avoid the solvent becoming trapped: an occurrence that is even more likely when woods used with deep-pored wood.

A thinner has been used that’s not suited to the type of coating.

The rapidity of the thinners must be adjusted based on the product and from the application conditions. If the solvent is too slow, for example, it can become trapped, in part, within the film as a result of an increase in viscosity caused by the film-forming process and thus bubbles can form that are then unable to reach the surface and/or burst. Choose the thinner type carefully based on the substrate and the application conditions, where necessary seeking the advice of the technical support department.

Substrate temperature too low or room humidity levels too high (especially for in-line coating).

Conditioning or pre-heating the substrates for move a temperature of at least 15°C to stop the coating evaporating too quickly when it goes through the hot area of the tunnel, thus causing bubbling.

Excessive air pressure used during application.

Always keep to the recommended pressure based on the type of equipment you’re planning to use.

Nozzle used is the wrong size.

Make sure you’re using the correct air pressure as well as the correct thinner type for the size of the nozzle, surface dimensions and room temperature.

Water coming out of the compressor or from the spray booth water wall.

Use an appropriate air filter system on the compressor. Check the compressor at regular intervals and empty the oil water separator. Thoroughly clean the spray booth water wall.

Pump filter clogged.

Be thoroughly a lot when cleaning filters in high-pressure systems. The high pressure in airmix and airless systems often can cause to force the product coming out from very dirty filter cartridges, but results in a lot of air being incorporated into the layer of coating being applied.

BRITTLENESS

Is the coating film cracking?

solution

A cracked coating is a sign of an excessively rigid system and this problem is evidenced by the coating splitting and peeling off.
The only way to eliminate the problem of a brittle coated surface is to sand the dried film back to the bare substrate with 80 grit sandpaper and to apply a new coating system starting from the first coat.
Alternatively, in less critical cases, sand out the defect completely using 320 grit sandpaper and recoat.
Whatever the case, before recoating, you will need to identify and fix the cause of the problem.
Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

Incorrect mixing process: too much curing agent or accelerator.

Make sure you mix the coating’s parts correctly and in the right proportions. It’s always best to use scales rather than mixing the parts by volume.

A thinner has been used that’s not suited to the type of coating.

Change the thinner appropriate for the product and the application conditions.

Product’s pot life has expired.

Always comply with the product’s pot life as given on the technical data sheet, remembering that this can vary depending on the mixing and local climatic conditions.

In PU systems, an unsuitable hardener has been used.

Use a more elastic hardener, following the technical department’s recommendations.

Application temperature is too low (water-based products).

Water-based products need heat to form a film properly.
Do not apply on substrates or with room temperatures below 15°C.

BROWN STAINS ON JOINERY

Are you seeing brown patches on the windowsill outside?

CAUSE

With exterior shutters made from timber species rich in tannin extractives – such as oak, chestnut or framirè – following heavy rains, you might see a brown-coloured liquid bleed out of the ends of the boards, ending up on the windowsill. Tannin can be extracted by rainwater as there is raw wood inside the joints where the staves slot together and, because it’s not protected by the coating, this raw wood is prone to releasing tannin.

SOLUTION

There are two stages to tackling this problem.
Removing the yellowish stain from the windowsill or structure: clean using a 5% sodium hypochlorite solution (sold in pharmacies), then rinse off with plenty of water. If the windowsill is made from marble, make care will be needed. Apply Linea Blu KK1112 reviver oil to seal the ends of the windowsill.

CHIPPING

Does the dried coating film break around contours?

SOLUTION

The only way to eliminate the problem of chipping on the coated surface is to sand the dried film back to the raw substrate with 80 grit sandpaper and apply a new coating system starting from the first coat.
Whatever the case, before recoating, you will need to identify and fix with the cause of the problem.
Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

Poor adhesion (see ADHESION and BRITTLENESS).

End effects of cracking (see ADHESION and BRITTLENESS).

Excessive pressure used during application.

Make sure you’re using correct air pressure as well as the correct thinner type for the size of the nozzle, surface dimensions and room temperature.

Coating building up too much in milled parts.

Localised build up of coating material can cause excessive shrinkage in volume during drying. In you’re not happy with the end appearance (covering with pigmented products, for example), don’t carry on applying more of the same product; instead, apply a number of layers, sanding between coats, or choose a product and/or curing agent that is more elastic, also taking into account the type of substrate and the stress it will be required to withstand.

CISSING

Is the coating film cissing?

SOLUTION

The only way to eliminate the problem of cissing on the coated surface is to sand out the defect completely using 320 grit sandpaper and recoat.
Anyway, before recoating, you will need to identify and fix with the cause of the problem.
Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

Surface contaminated by oil, silicone or other external agents.

Remove any grease from the substrate thoroughly using acetone or deep sanding to remove contaminants from the surface. Use an appropriate additive to avoid cissing.

Water or oil coming out of the compressor.

Use an appropriate air filter system on the compressor. Check the compressor at regular intervals and empty the oil water separator. Use an appropriate additive to avoid cissing.

Other types of contamination such as hand cream, sweat on hands, local businesses using silicone derivatives, waxy detergents, etc.

Identify the types of silicone and adopt the most appropriate solution and fix with them. Use an appropriate additive to avoid cissing.

Coating product and/or coating environment contaminated.

If it’s the coating product that’s been contaminated, a small amount of an anti-cratering additive might solve the problem.
If contamination is more serious, determine the source and allow air to circulate for a few hours through the spraying area to clean the environment (in some cases, air might have to be allowed to circulate for a whole weekend).

COLOUR RUBBING OFF JOINERY

Do you get colour on the wipe when cleaning joinery?

CAUSE

This problem is absolutely no cause for concern. Resins used in formulating water-based coatings are acrylic in nature and, for greater outdoor resistance, have elastic properties. This elasticity also gives the water-based coating a certain thermoplastic quality, i.e. the property of softening under the influence of heat. The action of rubbing generates heat on the surface, causing the coating to soften and thus meaning the pigments, which are found not only inside the film but on the surface, too, are sensitive to rub off. Since the layer of product removed is infinitely small, there is no discernible decrease in the coating’s outdoor protection. After the first few cleanings, this phenomenon will become much less noticeable.

SOLUTION

Clean external joinery using a soft cloth and Linea Blu HH8011 cleaner, which has been specially designed to clean without being harsh on the films formed by water-based coatings. Do not rub too hard with the rag.

COVERING

Is the product not hiding the underlying surface properly?

SOLUTION

In most cases, if poor hiding is the only issue encountered, all you need to do is sand the surface and apply subsequent coats until you’re happy with the appearance, within the recommended application limitations stated on the technical data sheet. Below is a list of some of the possible causes of products producing poor hiding results.

HOW TO AVOID THE PROBLEM

Coating not mixed enough before to use.

Mix the coating thoroughly before adding the hardener, then stir again the resulting mixture well after adding the thinner.

Coating applied too thinly.

Always comply with the recommended weights given on the technical data sheets.

Coating with low solids content.

Use coatings with higher solids content.

Substrate not compatible (e.g. reconstituted veneers).

Use suitable primers to stop the substrate absorbing the coating material.

In pigmented systems, the basecoat has been sanded too aggressively, to the point of removing the pigmented basecoat entirely, thus exposing the MDF underneath.

Do not sand the substrate too forcefully or for too long, especially with automatic or manual equipment. This is particularly important for critical areas, such as sharp edges or anywhere close to the edge of the item.

Coating absorbed by the substrate (like chipboard, reconstituted veneers, hardboard, etc.).

Adjust the coating system to suit the substrate, applying specific sealers, increasing the number of coats of finish applied or using products with greater viscosity.

CRACKING

Is the coating film cracking?

SOLUTION

The only way to eliminate the problem of cracking on the coated surface is to sand the dried film back to the raw substrate with 80 grit sandpaper and apply a new coating system starting from the first coat. Anyway, before recoating, you will need to identify and deal with the cause of the problem. Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

Incorrect mixing process: too much curing agent or accelerator (polyester coatings).

Make sure you mix the coating’s parts correctly and in the right proportions and mix thoroughly prior to application.
It’s always best to use scales rather than mixing the parts by volume.

A thinner has been used that’s not suited to the type of coating.

An incompatible thinner can damaged the quality of the film and/or compromise its adhesion and chemical and physical properties, causing in brittleness and cracking or deterioration in adhesion and wetting of the substrate.
Choose the thinner carefully to suit the nature of the product and application conditions.

Wrong overcoating interval: insufficient drying time.

If the film of the previous coat applied in a wet-on-wet system is not sufficiently strong, it can be torn from the substrate, causing cracks.
Always keep to the recommended overcoating intervals based on local climatic conditions and adjust the amount and type of thinner to suit application conditions.

A new film has been applied over a coating that has already dried.

If you don’t know the nature of the dry film, always make sure that the new coating system cycle is compatible with the furniture’s existing coating.
Whatever the case, always sand the substrate first with 320 grit paper before applying.

Initial product not mixed appropriately.

Make sure you mix the coating’s parts correctly and in the right proportions and mix thoroughly prior to application.
It’s always best to use scales rather than mixing the parts by volume.

In PU systems, an unsuitable hardener has been used.

If hardeners are too stiff or added in excessive amounts, they can cause stiffening or insufficient elasticity in the coated layer.
Use a hardener with better elasticity properties and make sure it’s compatible with the product used. Abuot that, please contact the technical department’s advice in this regard.

Too much material applied.

Any build up of coating dried film, even if only local, can cause excessive shrinkage in volume during the drying stage. In you’re not happy with the end appearance during application (for example, covering with pigmented products), don’t try to correct it by carrying on with applying more of the same product in a single coat; instead, apply it in a number of lighter coats, sanding between coats, following the directions on the technical data sheet.
If this isn’t possible, use a product and/or curing agent that is more elastic, taking into account the type of substrate and the stress it will likely be required to withstand, keeping in mind the limits set out on the technical data sheet.

Excessive ventilation in flash-off of water-based products.

Excessive ventilation or heat can dry the coating film too quickly.

DIRT

Is there dirt on the surface of the coating film?

SOLUTION

The only way to correct this problem on a matt coated surface is to sand the dried topcoat (using P320 grit sandpaper) and recoat the whole area once you have identified and solved the causes of the defect.
If you find dust in gloss topcoats, you can sand lightly and then polish to eliminate the problem. Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

The surface of the substrate to be coated is dirty.

Wipe dust off all the surfaces of the panels (including ends).

Workplace is dirty.

You need to work in a thoroughly clean room to achieve a good result, especially when applying finishes with high gloss levels. Keep the workplace clean and, where necessary, wet or dampen surfaces around the coating area to stop dust being carried in the air.

Coating material is contaminated.

Filter the coating material with a suitable filter after mixing it.

Dust or gelled particles of coating material contaminate the product on opening the tin.

Remove dust or any gelled product residues from the lid of the can before using the coating material. Filter the coating material with a suitable filter after mixing it.

DRIP

Does the product drip during application?

SOLUTION

The only way to correct this defect on a coated surface is to sand the dried topcoat using 320 grit sandpaper and recoat the whole area once you have fixed with one or more of the above-mentioned causes.

HOW TO AVOID THE PROBLEM

The wet coating film is overly thick.

Reduce the amount of product applied.

Application too wet.

Restore correct application parameters, closing the gun’s nozzle and spraying in a number of passes to balance out the appearance.

Thinner too slow.

Use faster evaporating thinners.

Spray gun too close to the part to be coated.

Hold the gun further away at the right distance.

Air pressure too low.

Increase air pressure, applying the product in a number of coats to avoid creating too much thickness.

Product viscosity low.

Check the percentage of thinner in the mixture and make sure that its temperature is not too high (high temperatures cause a drop in viscosity and increase the coating more fluid).

Unsuitable product, especially for applications on vertical surfaces.

Choose the most appropriate coating based on the manufactured product to be coated and the application conditions.

DYE BLEEDING

Does the dye dissolve when the basecoat is applied on the stained substrate?

Unsuitable stains used during the coating process.

Make sure you use an insoluble stain containing pigments or colourants that have low solubility.

SOLUTION

The only way to solve this problem consists in removing all previous hardened layers of coating from the coated surface, sanding with P80 grit sandpaper, and recoating from the beginning.

Does the dye dissolve when the basecoat is applied on the stained substrate?

Unsuitable solvents used as thinners for the coating.
Change the thinner to suit the nature of the coating, local climatic conditions and the nature of the wood.

SOLUTION

The only way for fix this problem consists in removing all previous hardened layers of coating from the coated surface, sanding with P80 grit sandpaper, and recoating from the beginning.

Does the dye dissolve when the basecoat is applied on the stained substrate??

No binder or use of an unsuitable binder.
Add more binder or use the right one, referring to the technical data sheet or seeking the advice of the customer support department.

SOLUTION

The only way for fix this problem consists in removing all previous hardened layers of coating from the coated surface, sanding with P80 grit sandpaper, and recoating from the beginning.

DRYING ISSUES

Has the coating film failed to harden completely?

SOLUTION

In the event that drying is being slowed down by the temperature, wait longer to allow the coating to dry completely. If this is not possible, the only solution is to sand the dried film back to the raw substrate with 80 grit sandpaper and apply a new coating system starting from the first coat.
Whatever the case, before recoating, you will need to identify and fix with the cause of the problem. Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

Surface contaminated by oil, silicone or other external agents.

Remove any grease from the substrate thoroughly using acetone or deep sanding to remove contaminants from the surface. Apply specific sealers.

Incorrect mixing or incorrect amount of curing agent, accelerator or photoinitiator.

Make sure you mix the coating’s parts correctly and in the right proportions. It’s always best to use scales rather than mixing the parts by volume.

A thinner has been used that’s not suited to the type of coating.

Change thinner suit the product and spraying conditions.

Wrong overcoating interval: insufficient drying time, resulting in solvent becoming trapped, leaving the film soft.

Always keep to the recommended overcoating intervals based on the type of coating used and local climatic conditions and adjust the amount and type of thinner so that exposure to lamps and curing time are correct and match production requirements.

Coating applied on top of another previous film applied with an incompatible coating.

Make sure you only use coatings that are compatible with each other.

Drying area too cold.

Spraying should be carried out at a temperature in the 20–25°C range. The thinner and curing agent should be chosen based on the spraying conditions. If the humidity level is too high, it can cause an excessive chemical reaction, resulting in brittleness issues (see BRITTLENESS).
If the cause is only the temperature, simply wait longer or increase the drying temperature to ensure the coating cures fully (solvent-based products).
Water-based products, on the other hand, are unable to form a film below a certain temperature and, under such conditions, produce brittle films that are prone to peeling (see BRITTLENESS).

Too little or too much air circulation within the drying area.

Fine-tune the flow of air coming out of the distribution system to ensure correct air circulation.

Poor UV lamp efficiency (over 2,000 hours of operation).

Replace UV lamps.
In some cases, the defect can be remedied by putting the panels through the curing cycle a second time.

Line speed too fast (UV products).

Reduce the line speed or replace the coating with a more reactive one better suited to the line’s requirements.
In some cases, the defect can be remedied by putting the panels through the curing cycle a second time.

Excessive amount of product applied (especially for synthetic or physically cured coatings).

Always comply with the recommended weights given on the technical data sheets.

Excessive solvent concentration in area around coated panels.

Install suitable extraction and ventilation in the room in order to extract solvents evaporating from the drying film. These solvents can saturate the room, resulting in softening of the coating film, which needs longer times to complete film forming.
Wait long times enough for the coating to fully cure; if this isn’t possible, sand and repeat the coating system with suitable products.

Hardener damaged (for PU systems).

The hardener is very sensitive to humidity of the air, with which it tends to react irreversibly. Before using the hardener, check that it is clear and transparent. If it looks at all milky, throw away the tin and use a new one. Always seal cans of hardener securely after use.

FADING

Having problems with the substrate fading?

Stains used that aren’t lightfast.
Make sure you use a lightfast stain.

SOLUTION

The only way to eliminate this problem on the coated surface is to sand back the whole dried film on the substrate with 80 grit sandpaper and apply a new coating system starting from the first coat.

Having problems with the substrate fading?

Polyester coatings applied without suitable sealers.
Use a suitable sealer to retain the colour of the previously applied stain.

SOLUTION

The only way to eliminate this problem on the coated surface is to sand back the whole dried film on the substrate with 80 grit sandpaper and apply a new coating system starting from the first coat.

Having problems with the substrate fading?

The coating film yellows with age (especially when using nitrocellulose or PU coatings without low-yellowing hardeners).
If you want to be sure of avoiding this problem, only use acrylic or water-based non-yellowing systems or, to limit the phenomenon, polyurethane systems using low-yellowing hardeners.

SOLUTION

The only way to eliminate this problem on the coated surface is to sand back the whole dried film on the substrate with 80 grit sandpaper and apply a new coating system starting from the first coat.

GLOSS

The colour on the coated surface is uniform, but is it too leveling effect and missing gloss?

Stain used is resistant to bleeding through the coating film (generally pigment based).

Together with the bleed-resistant stain, also use small percentages of more soluble colourant-based stains that thus will bleed partly through the subsequently applied coating film, giving the colour a certain amount of gloss and depth. Alternatively, when dealing with water-based stain, use AC2110: these stains are bleed resistant and insoluble but have high bright levels and depth of colour.

SOLUTION

You can sand the topcoat with P320 grit sandpaper and reapply the coating with the addition of a very small percentage of soluble colourant. Caution: this remedy may result in a colour that is slightly different to the original colour. In addition, a soluble colourant can migrate to the surface of the coated film meaning that when the coated manufactured product is cleaned – or even during high-wear use – some of the colour can be transferred to the material in contact with the coated item.

INCONSISTENT MATT FINISH

Is the film’s matt finish uneven?

SOLUTION

The only way to correct this defect on a matt coated surface is to sand the dried topcoat using 320 grit sandpaper and recoat the whole area once you have dealt with one or more of the above-mentioned causes.

HOW TO AVOID THE PROBLEM

A thinner has been used that’s not suited to the type of coating.

Use a different thinner to suit the product and application conditions.

Coating applied using inappropriate equipment.

With matt products, it’s especially advisable to always use an assisted coating system, such as an airmix system (with pumps) or a traditional spray gun. These systems can give better product leveling over the substrate and good thinner release from the applied film. When applying using a curtain coater, use a product designed specifically for this purpose.

Too little or too much air circulation in the drying area.

If the film dries too quickly or too slowly or unevenly, matt finish inconsistency problems can be caused by the matting agent coming to the surface unevenly in different areas.
Fine-tune the flow of air coming out of the distribution system so as to encourage the release of the solvent.

Line speed too high.

When coating on automatic lines, reduce the line speed or replace the coating with one better suited to the line’s requirements.

Too much product applied

Always comply with the recommended weights given on the technical data sheets.

Product applied in an uneven amount on the substrate.

Make sure you apply the coating in an even thickness across the whole surface to be coated.

With UV products, the exposure to low-pressure lamps was not long enough.

Keep to the recommended times on the technical data sheets.

Finish not mixed sufficiently.

Mix well prior to use to ensure any solids that have settled at the bottom of the tin are properly dispersed.

Room temperature: in some cases, gloss levels can differ between summer and winter.

Change the thinner and/or curing agent as advised by the technical department.

JOINERY CHALKING

Are whitish powder-like patches appearing on joinery?

CAUSE

This phenomenon occurs on shutters made from marine plywood with phenolic glue. From the moment they are produced, phenolic glues contain a varying percentage of caustic soda as a stabilizer. Water-based coatings, as a result of their water permeability, encourage the caustic soda to solubilise and hence migrate towards the joinery’s outer surface, where it settles in the shape of a light flour-like white powder. The fact that the phenomenon is observed above all in early spring (when the wood loses moisture) and is more pronounced on joinery exposed on the dampest side of the house shows that the issue is linked to the wood absorbing water through the coating film.

SOLUTION

This phenomenon does not affect the durability of the actual coating in any way. All you need to do is to clean the joinery as you would normally. Once the joinery has been cleaned, the phenomenon may reoccur within a few weeks, though it will be less evident, and will eventually disappear altogether.

JOINERY FADING

Has the colour on the exterior part of the external joinery changed?

CAUSE

Wood is made up of cellulose, lignin and extractive substances of various kinds that can degrade by the ultraviolet component of sunlight. In the case of woodwork coated with clear finishes (i.e. finishes that let the wood show through), this translates over time into a slight change to the colour of the wood. Just how much it changes will depend upon the exposure to sunlight, the type of wood and colour of the wood protective stain.

Wood can distinguish into two types: Light wood (e.g. pine, fir): wood exposed to sunlight can go yellow or brown owing to the products that form as the lignin contained within the wood’s cells breaks down. Dark wood (e.g. meranti, oak): wood exposed to sunlight can fade as the extractive substances contained within the wood’s cells – which are responsible for the colour of the wood species – break down. This colour changing is more evident in wood that has a deeper coloured grain as its natural component substances are easily broken down by sunlight.

Wood stain colour: varnishes for exterior use contain special filters capable of absorbing the sun’s UV radiation. These filters, depending on the amount of sunlight they are exposed to, wear out over time, thus losing some of their protective effect.

SOLUTION

For external joinery in a clear colour and in a very exposed position and/or installed in hot countries, apply Linea Blu KK1112 reviver oil using a rag at 6-month intervals.

EXTERIOR JOINERY MAINTENANCE

How do you maintain EXTERIOR joinery?

To keep woodwork exposed outdoors at its best and ensure lengthy service life, it needs regular checking and attention. Wood exposed outdoors is subjected to slow and continuous degradation by the surrounding environment that painting or varnishing alone cannot stop, though it can slow down the process. Consequently, a thorough inspection generally carried out twice a year (once before summer and once before winter) to assess the state of repair of the coating film can allow you to prevent deterioration of the woodwork, keeping it in tip-top condition at all times. Don’t wait for the surface film to be completely ruined before starting treatment of whatever kind. Prevention is better than cure!!! Generally speaking, when dealing with light-coloured wood stains or coniferous woods, it’s even more important to check surfaces at regular intervals and touch up any damaged parts without delay. The main maintenance measures are: cleaning, revitalising, touching up, restoring, repairing.

JOINERY MAINTENANCE

How do you clean of the external joinery?

OBJECTIVE

Cleaning a manufactured product exposed outdoors is the first important step in maintaining your external joinery properly. Phenomena such as acid rain and atmospheric pollution tend to reduce the coating’s service life. Removing grease, smog and anything else that has been deposited on the surface of the coating is a great start to ensuring your external joinery lasts longer.

MATERIALS

Under no circumstances use harsh cleaners, such as alcohol- or ammonia-based products. These products attack the coating film, thus damaging the surface, which is detrimental to the whole item. Instead, use mild cleaners like Linea Blu HH8011, which clean just as well but without damaging the coated surface. Use a soft cloth without rubbing too hard.

PROCEDURE

Apply mild cleaner HH8011 to the cloth and wipe over the surface, working in circles, after dry with a soft cloth.

FREQUENCY

Every 6 months, before the start of summer and before the start of winter.

JOINERY MAINTENANCE

How do you revitalise the external joinery?

OBJECTIVE

This operation must be carried out on a film in good condition that has not yet been damaged (no cracking of any kind). The aim is to restore the outer protective layer’s original appearance and give the manufactured product greater water repellence in order to leave it better protected against the damaging effects of water.

MATERIALS

Mild cleaner HH8011, reviver oil KK1112 and a soft cloth.

PROCEDURE

First clean the joinery thoroughly with mild cleaner HH8011. No sanding is required for this operation, which is very simple to perform: simply apply reviver oil KK1112 with a soft cloth, working in circles, and making sure you remove any excess. It’s easy to carry out and is not very time consuming. Next, allow to dry for a few hours. Caution: when applied to white pigmented topcoats, the reviver oil tends to make them go yellow. Do not apply an overly generous amount or you risk the whitening of the film.

FREQUENCY

One year after installation, and at least twice a year after that: before winter and before summer.

JOINERY MAINTENANCE

How do you touch up joinery?

OBJECTIVE

To stop water getting in through any breaks in the coating film and consequently seriously damaging the wood underneath (greying, mould growth, etc.) and resulting the film coming away from the wood.

MATERIALS

Brush with a combination of animal/synthetic bristles, Linea Blu HF204X water-based clear topcoat in your chosen colour or Linea Blu HL206X water-based pigmented topcoat in your chosen colour.

PROCEDURE

Only treat the part to be touched up. First, check the item for any surface deterioration, then clean the surface with HH 8011. The next step is to touch up only the damaged part using a brush to apply the water-based Linea Blu HF204X or HL206X coating in your chosen colour. Once dry, check to make sure that the continuity of the film has been restored, otherwise repeat the touch-up step. For best aesthetic results, you can extend the touch-up to the whole joinery component (e.g. stile, transverse, jamb, etc.). In this case, follow the same procedure given for restoration, taking the following two precautions: use the colourless clear topcoat HF2040, to avoid differences in colour, and check to make sure that the continuity of the film has been restored.

FREQUENCY

Visual inspection every 6 months, before the start of summer and before the start of winter.

JOINERY MAINTENANCE

How do you restore the external joinery?

OBJECTIVE

The aim is to restore the original outer protective layer that has not yet been damaged irreparably (no cracking of any kind), given that it slowly loses its ability to protect the wood over time. Hence, action is required to prevent the coating film losing its protection properties (e.g. absorbing UV radiation, etc.) as this would cause the woodwork to deteriorate quickly and suddenly, with the coating peeling and the wood going grey.

MATERIALS

240 grit sandpaper, brush with a combination of animal/synthetic bristles, water-based clear topcoat HF204X in your chosen colour and exterior wood stain HI201X in your chosen colour or water-based pigmented topcoat HL206X in your chosen colour.

PROCEDURE

Clean the surface thoroughly and remove any grease. Sand with 240 grit paper, then apply a coat of Linea Blu HF204X or HL206X water-based coating in your chosen colour using a brush or spray gun across the entire manufactured product. If any areas have been sanded back to raw wood, apply exterior wood stain HI201X in your chosen colour, only to the area in question before proceeding with the topcoat.

FREQUENCY

Every 4-6 years depending on exposure levels.

JOINERY MAINTENANCE

How do you repair of the external joinery?

OBJECTIVE

This operation is required on surfaces that are seriously damaged, with the coating film clearly cracking and peeling off and the wood greying. This deterioration is largely attributable to failure to perform previous maintenance work.

MATERIALS

240 grit sandpaper, brush with a combination of animal/synthetic bristles, water-based clear topcoat HF204X in your chosen colour and exterior wood stain HI201X in your chosen colour or water-based pigmented topcoat HL206X in your chosen colour.

PROCEDURE

Repairing the item properly involves mechanically sanding away the old damaged film completely (starting with 60 grit sandpaper and then progressing to 100 grit). If you are using a paint remover to remove the coating, you will then need to wash the surfaces and, at the very least, wait a few days before starting treatment. Next, fill any cracks and holes and then sanding again, this time using finer sandpaper: 150-180. At this point, you can start the recoating system, applying water-based exterior wood stain HI201X in your chosen colour. Allow to dry for 2 hours and then finish by brushing or spraying on two or three coats of clear topcoat HF204X or HL206X in your chosen colour. Sand prior to the last coat with 240 grit paper.

FREQUENCY

There is no way for us to define a set frequency as it very much depends on the level of outdoor exposure. Based on our current experience, this frequency can range from 10 to 15 years. This action is required in exceptional circumstances to deal with pronounced surface deterioration.

JOINERY SWELLING

Has the shutter swollen?

CAUSE

Wood is a hygroscopic material that tends to absorb and release moisture depending on external environmental conditions. This means that wood, even once coated, experiences a certain amount of internal movement according to the way external humidity is being absorbed or desorbed. Given their tongue-and-groove construction, outdoor shutters are one of the items most greatly affected by this distinctive property of wood. Indeed, following long periods of high ambient humidity (e.g. fog) or persistent rain or snow, the problem of swelling can appear on the sides facing out, resulting in the shutter becoming misshapen and hard to open and close.

SOLUTION

As soon as the high atmospheric humidity has passed, the shutter will just about return to its original size. Do not plane the shutter. After the first two or three times it swells as a result of humidity in the atmosphere, the wood will stabilise and this problem will not be experienced further. Should the problem persist, check the hardware adjustments.

LEVELING

Problems with “orange peel” or excessive texture?

SOLUTION

The only way to correct this defect on a coated surface is to sand the dried topcoat using 320 grit sandpaper and recoat the whole area once you have dealt with one or more of the above-mentioned causes.

HOW TO AVOID THE PROBLEM

Excessive viscosity of coating.

Decrease the coating’s viscosity by adding the right amount of a suitable thinner.

Thinner not suitable.

Only use the recommended thinners.

Spray gun held too far away from the substrate to be coated.

Hold the gun closer to the substrate while spraying.

Nozzle used is too small.

Use an appropriately sized nozzle.

Product not suitable for spraying.

Use the right product.

Air pressure too high.

Adjust the air pressure based on the application.

Underlying coat not sanded properly.

Sand whilst making sure that you level the dried coated surface perfectly without leaving dips or unsanded patches.

Coating or room temperature too low.

Increase the room temperature. Pre-heating the coating prior to use and make sure the place where it’s stored is at a suitable temperature. Avoid temperatures that are too high as this would result in the same leveling issue, this time due to the coating film applied drying too quickly.

LIFTING

Does the topcoat start to crease and wrinkle once applied on top of the basecoat?

SOLUTION

The only way to correct this defect on a coated surface is to sand the dried topcoat using 320 grit sandpaper and recoat the whole area once you have dealt with one or more of the above-mentioned causes.

HOW TO AVOID THE PROBLEM

Basecoat not completely dry.

Keep to the recommended drying times.

Incorrect amount of hardener in PU systems (during mixing) in the basecoat.

Mix part A with the right percentage of hardener (see the technical data sheet of the product used).
Note: the only way to eliminate/remedy the problem, if this is the cause, is to sand the dried film back to the raw substrate with 80 grit sandpaper and apply a new coating system starting from the first coat, given that it’s practically impossible to fix the problem with persistent sanding and/or additional coats (the basecoat would continue to lift).

Solvents in the topcoat are too aggressive.

Use a product with less aggressive solvents.

Incompatibility between different coatings (e.g. nitrocellulose basecoat and PU topcoat).

Do not use combination coating systems unless following the advice of the customer support department to the letter.

OVERSPRAY

Are there powdery patches on the coated manufactured product?

SOLUTION

Where overspray has not harmed or impeded adhesion (check to ensure this has not happened), normal sanding with 280 or 320 grit paper followed by the application of a new coat of topcoat can solve the problem. If you encounter adhesion problems, you will need to remove all of those layers of coating that have already hardened, sanding with 80 grit sandpaper, and recoat from the beginning.
Anyway, before recoating, you will need to identify and deal with the cause of the problem.
Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

A thinner has been used that’s not suited to the type of coating.

Use of unsuitable thinners (such as ones that are too fast or offer poor wetting) can inhibit the re-absorption of overspray on the portion of substrate that’s already been coated or the adhesion of powder on unprotected surfaces (e.g. furniture that’s already been assembled).
Use the thinner best suited to the type of coating and application system.

High pressure used during application.

If pressure is too high, the coating material can be excessively atomised and result in the premature and excessive loss of solvents, with a consequent deterioration in aesthetic and performance qualities, in addition to causing overspray issues.
Make sure you’re using the correct air pressure for the nature of the coating, surface dimensions and room temperature.

Nozzle used is the wrong size.

If the nozzle is too fine, the coating material can be excessively atomised and result in premature and excessive loss of solvents, with a consequent deterioration in aesthetic and performance qualities, in addition to causing overspray issues.
Choose the right nozzle for the nature of the coating, surface dimensions and room temperature.

PINHOLES

Are little holes visible in the basecoat after sanding?
(see also BUBBLING)

SOLUTION

The only way to correct this problem is to sand the dried topcoat using 320 grit sandpaper and to recoat the whole area once you have dealt with one or more of the above-mentioned causes.

HOW TO AVOID THE PROBLEM

Drying too fast: direct heat on the substrate, high room temperature during solvent flash off, etc.

Adjust temperature to appropriate levels.

Application viscosity is too high.

Thin the coating until to obtain the optimal level of viscosity.

Coating applied is too thick.

Apply less material in accordance with the product’s technical data sheet.

Thinner used is too rapid.

Use an appropriate thinner based on the application conditions.

Thinner contaminated with water (solvent-based products).

Only use thinners that you’re confident are of good quality (urethane grade).

PORE BYPASSING

Is the coating failing to wet the pore properly and building up around its edges?

SOLUTION

Given that it is practically impossible to fix the problem by means of persistent sanding and/or additional coats, the only way to eliminate the problem of the coating bypassing the pore on the coated surface is to sand the dried film back to the raw substrate with 80 grit sandpaper and to apply a new coating system starting from the first coat. Because is impossible fix it, insisting with sanding and/or other layers. Anycase, before recoating, you will need to identify and fix with the cause of the problem. Below is a list of possible causes and relevant solutions.

HOW TO AVOID THE PROBLEM

Base and topcoat not suited to the system.

Use products with more wetting property for the first coat or apply a coat of suitable sealer directly to the substrate before any basecoats.

Coating viscosity too high

Increase the amount of thinner used to lower the coating’s viscosity and thus encourage its penetration into the pore.

PORE MARKING

Is there little colour in the pores on the substrate?

Failure to use a suitable binder in spray-applied stain.

Use a binder that is suitable for marking the pore in the stain-thinner mixture based on the nature of the stain.

SOLUTION

The only remedy to this problem is to remove all previous hardened layers of coating from the surface, sanding with P80 grit sandpaper, and recoating from the beginning.

Is there little colour in the pores on the substrate?

Stain thinner too rapid.
Use a slower drying thinner to allow for better pore wetting.

SOLUTION

The only remedy to this problem is to remove all previous hardened layers of coating from the surface, sanding with P80 grit sandpaper, and recoating from the beginning

Is there little colour in the pores on the substrate?

Substrate with deep pores that are hard to wet (like oak).
Apply the stain using a wipe or use a suitable binder. Alternatively, use a colourant series like AC2110/XX, which has excellent pore-marking properties.

SOLUTION

The only remedy to this problem is to remove all previous hardened layers of coating from the surface, sanding with P80 grit sandpaper, and recoating from the beginning.

RESIN

Resin bleed issues?

SOLUTION

The only way to eliminate the problem of resin bleed affecting the coated surface is to sand the dried film back to the bare substrate with 80 grit sandpaper and apply a new coating system starting from the first coat.
The most common, if not the only cause is the use of coniferous woods with a lot of knots and with a high resin content.

HOW TO AVOID THE PROBLEM

Do not use this kind of woods, especially for lacquered systems. If this is unavoidable, there’s no coating system that can stop resin bleeding out of wood completely. The best you can do is to mitigate the phenomenon by first cleaning the substrate of the resin that has bleed out using a synthetic thinner and, once completely dry after 24 hours, apply specific products: for interior systems, use sealer TR5008; for pigmented exterior systems, use a two-pack product (both water-based and PU).

RISK SITUATIONS FOR JOINERY

What situations put joinery at risk?

Joinery coated with colourless or natural systems.

Exposure to corrosive or aggressive environments (e.g. areas within 200 metres of chemical plants, refineries, industrial dry cleaners, etc.).

Exposure to harsh natural environments: e.g. areas within 200 metres of the high tide mark (sand, sea spray, etc.) or exposed to sources of heat in excess of 70°C (measured on the joinery) or, in any case, installed higher than 2,000 metres above sea level.

Damage from hail and natural disasters.

Joinery in a state of disrepair and neglect (e.g. houses left empty for at least a year, no maintenance procedure in place for joinery, etc.).

Wood swelling attributable to excessive ambient humidity (e.g. joinery installed in rooms where flooring work is performed without the required ventilation).

White haze appearing on the coating owing to prolonged contact with water during the first few months after the joinery is installed.

Transformations or modifications to the external face of the window by the user of the window

Touch-ups carried out using products that have not been recommended by the external joinery manufacturer.

Use of chemicals other than commercially available mild cleaner for cleaning external joinery.

The usage conditions of the joinery fall outside usual ranges.

High levels of humidity in the atmosphere (e.g. persistent fog and/or rain and/or snow lasting more than 15 days).

Damage caused by splashes, accidental pouring or paint drips with products used on building sites, such as wall paints, concrete, enamels, lime, plaster, etc. Protect joinery with plastic sheeting (e.g. polyethylene).

Exposure in areas where the surface of the joinery drops below -20°C or reaches more than 60°C (e.g. Siberia, Middle East etc.).

SANDING

Does the coated manufactured product have sanding-related issues?

SOLUTION

The only way to eliminate sanding problems on the coated surface is to remove from the defective film back to the raw substrate with 80 grit sandpaper and apply a new coating system starting from the first coat. To remove the marks left on the basecoat by overly coarse sandpaper, use appropriate sandpaper to sand the coated surface to remove the marks and reapply the topcoat.

HOW TO AVOID THE PROBLEM

Sanding marks on the basecoat

Sandpaper (or glasspaper) is used to sand wood to be coated or to sand previously applied layers of coating and it must be chosen carefully. Different types of abrasive are recommended depending on the film.
Polyester coatings: use silicon carbide paper.
Polyurethane coatings: use open-coat sandpaper.
Nitrocellulose coatings: use aluminium oxide paper.
Water-based coatings: use zinc stearate papers.
The various paper types are rated with a number that refers to the mesh size/number of openings per square inch in the screen used to sieve the abrasive grains identified by that number. The most common types of sandpaper are:

GRIT
40-60-80 big coarse
100-120-150 coarse
180-200-240 medium
320 fine
400-500-600 very fine
800-1000 ultra fine for polishing

Basecoat not completely dry.

If the basecoat hasn’t been allowed to dry completely, it can feel rubbery on sanding, clog the sandpaper and/or become etched or overly polished. Allow the basecoat to dry for the correct length of time.

SCRATCHING

The coating has very little scratch resistance?
(see also DRYING ISSUES)

SOLUTION

The only way to correct this problem is to sand the dried topcoat using 320 grit sandpaper and recoat the whole area once you have dealt with one or more of the above-mentioned causes.

HOW TO AVOID THE PROBLEM

Product not suitable.

Use a coating specially formulated to provide excellent scratchproof performance or introduce a specific additive like XT 4037/00 (see technical data sheet).

Thinner used is too slow, resulting in surface softening.

Use an appropriate thinner based on the application conditions. Waits the film to cure fully. Increase the curing stage temperature.

UNEVEN STAINING LACK OF CONSISTENCY

Does the stained substrate have areas of uneven colour?

Incorrect air pressure.

Adjust the air pressure such that the product is applied in homogeneous amounts.

SOLUTION

The only solution is to sand all previous layers of coating that have hardened (with P80 grit sandpaper) and recoat from the beginning.

Does the stained substrate have areas of colour spot?

Spray too close.
Hold the gun farther away from the piece to be stained.

SOLUTION

The only solution is to sand all previous layers of coating that have hardened (with P80 grit sandpaper) and recoat from the beginning.

Does the stained substrate have areas of uneven colour?

Stain too concentrated for spray.
Increase the stain’s thinning and increase the number of passes during application.

SOLUTION

The only solution is to sand all previous layers of coating that have hardened (with P80 grit sandpaper) and recoat from the beginning.

Does the stained substrate have areas of uneven colour?

The stain contains harmonising pigments (like the solvent-based XM7100/XX or water-based AC1810/XX) and has been applied directly by wipe or has been reworked after spraying.
Do not use brushes or wipes for this type of stain or change to a different stain type.

SOLUTION

The only solution is to sand all previous layers of coating that have hardened (with P80 grit sandpaper) and recoat from the beginning.

Does the stained substrate have areas of colour spot?

Substrate features different coloured stripes.
Use stains with harmonising pigments (like solvent-based XP1880 and XM7100 or water-based AP121, AC1810 and AC2110)

SOLUTION

The only solution is to sand all previous layers of coating that have hardened (with P80 grit sandpaper) and recoat from the beginning.

Does the stained substrate have areas of colour spot?

Appropriate binder has not been used.
Use the binder recommended for your specific use (see technical data sheet).

SOLUTION

The only solution is to sand all previous layers of coating that have hardened (with P80 grit sandpaper) and recoat from the beginning.

WHITE EDGES

Does the stained substrate have unstained areas along its edges?

Stain fast drying.

Solvent-based stains are generally more susceptible to the problem than their water-based counterparts, which are better at penetrating into the wood and reaching edges even during drying.

SOLUTION

The only solution is to sand all previous layers of coating and stain that have hardened (with P80 grit sandpaper) and recoat from the beginning.

Does the stained substrate have unstained areas along its edges?
Stain too concentrated.

Increase the stain’s thinning and increase the number of passes during application.

SOLUTION

The only solution is to sand all previous layers of coating and stain that have hardened (with P80 grit sandpaper) and recoat from the beginning.

Does the stained substrate have unstained areas along its edges?
Geometrically complex substrate with deep edges.

Apply stain with a spray carousel guns or by wipe.

SOLUTION

The only solution is to sand all previous layers of coating and stain that have hardened (with P80 grit sandpaper) and recoat from the beginning.

Does the stained substrate have unstained areas along its edges?
When applying to chairs or profiles with pronounced edges, the stain settles on the sides of the edge without colouring it.

Use the most suitable application equipment and stain type and adjust the thinning (generally increasing the thinning and the number of passes, decreasing the air pressure in airmix applications).

SOLUTION

The only solution is to sand all previous layers of coating and stain that have hardened (with P80 grit sandpaper) and recoat from the beginning.

WHITENING ON JOINERY

Do you see clear whitish blotches when rain lands on the coating film before it has perfectly dried?

CAUSE

On contact with rainwater and/or dew, surfactants trapped in the coating film give rise to clear whitish blotches that disappear as soon as they are no longer under the influence of water (evaporation). These patches are due to the solubilising of the surfactant within the film. If the film then comes into contact with water a second time, this phenomenon doesn’t replay as the surfactant has already been drawn out during the first contact. It’s very important not to scratch at the white patch insofar as, because the film is in its non-hardened state and is still partly soft, it would be irreparably marred. You can remove water using a soft cloth without damaging the coating. This phenomenon diminishes with time to the point where it disappears altogether.

SOLUTION

If, on the other hand, you want to address the issue, once the whitish patches have disappeared and the external joinery is perfectly dry, you can proceed as follows.
If there is only a light white haze: clean the external joinery with white vinegar (thinned with one part water to one part vinegar) using a soft wipe and without rubbing too hard. Next, after waiting 30 minutes, can pass over with a damp wipe to remove any traces of the washing solution left behind.
Where the white haze is very pronounced: apply Linea Blu KK1112 reviver oil using a rag.

WOOD PROTECTION MAINTENANCE

How can you keep wood protected in the long term?

To keep woodwork exposed outdoors at its best and ensure a long service life, it needs regular checking and attention. Wood exposed outdoors is subjected to slow, continuous degradation by atmospheric agents and painting or varnishing alone is not sufficient to stop this altogether. Consequently, a thorough inspection generally carried out twice a year (once before summer and once before winter) to assess the state of repair of the coating film can allow you to prevent deterioration of the woodwork, keeping it in tip-top condition at all times. Don’t wait for the surface film to be completely ruined before starting treatment of whatever kind. Prevention is better than cure! Generally speaking, when dealing with light-coloured wood stains or coniferous woods, it’s even more important to check surfaces at regular intervals and to touch up any damaged parts without delay.

YELLOW STAINS ON JOINERY

Are you having problems with yellow patches in pigmented coating systems?

CAUSE

When using white or light-coloured pigmented systems applied on species like oak, iroko, chestnut or teak, slightly yellowish patches can appear within 2-3 months of installation, following the grain of the wood in mold and distribution, especially when humidity levels in the wood and/or ambient humidity levels are high. This phenomenon is caused to highly staining substances within the wood that, when solubilised by water, are extracted from the substrate and carried and incorporated into the coating. Similar issues are also encountered with western red cedar, merbau and wenge. The above-mentioned defect can also be seen when restoring old external joinery though, in this case, it can occur with all species of timber. This is caused to the fact that the substances resulting from the wood’s breakdown when exposed to sun and water are water soluble and have staining properties.

SOLUTION

Since these yellowish patches are made up of photolabile chemicals, just as they appeared, they will tend to disappear over time (generally within one to three months). Should the problem persist, contact our technical department.