failure that may arise during the application of a coating because air cannot leave the support, since coating englobes air from the support; difficulties in solvent evaporation; development of reaction gases. It results in the formation of cavities (bubbles) more or less persistent on the film.
| Defects | Solutions |
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Excessive thickness of applied product (the film dries more quickly on the surface, trapping the solvent, and resulting in the formation of bubbles)
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Reduce weight and add slow thinners to slow the drying of the film surface
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Elevated room temperature (the film dries more quickly on the surface, blocking the solvent evaporation, which remains trapped and forms bubbles)
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Add slower thinners to slow down the drying of the film surface
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Too high viscosity of the product applied (tendency not to release solvents)
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Reduce the viscosity with a suitable thinner
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Too high air pressure during spray application
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Spray at a lower pressure
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Surface with inadequate preparation (it “blows”, this means it does not wet properly, causing the formation of bubbles)
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Give another coat of primer or add anti-bubble in the polyurethane primer in curtain coating application
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Panel broken during sanding |
Use one more coat of primer, sanding it without breaking the panel.
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Use of cheap paint thinners, containing poor, unsuitable solvents
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Use thinner of suitable quality
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Too cold panel
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Pre-warm the panel
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Too high moisture of the surface or environment (the second polyurethane component, by reacting with moisture, forms carbon dioxide with subsequent development of bubbles)
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For a good coating, wood should have moisture between 8% – 14% and the humidity of the environment should not exceed 75%
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failure on a film of paint applied with a roller, with parallel crackings left on the surface of the panel.
| Defects | Solutions |
|---|---|
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Excessive quantity applied because of too high product viscosity
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Thin using a suitable thinner
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Very cold room temperature and cold product, which causes an increase in viscosity
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Warm up the room and/or thin the product using a suitable thinner
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Abnormal and frequent occlusion of the filters in the all application systems, caused by particles of resins, pigments, matting fillers, or foreign bodies.
| Defects | Solutions |
|---|---|
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Precipitation caused by the use of unsuitable thinners
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Check the type of thinner used
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Because of prolonged storage, the product shows a variety of impurities and precipitations
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Pre-filter the product before using it (see also Foreign particles)
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Use of dirty containers for product preparation / mixing
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Pre-filter the product before use
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Additives (e.g. matting agents) added in excess just prior to use
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Stir and shake well to obtain adequate dispersion
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The filters of the application equipment are too thin
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Replace filters with more appropriate ones
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Product is not enough ground and / or filtered
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Pre-filter the product before using it (see also Foreign particles)
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Issues with dry paint film
lack of adherence between a coating film and the surface on which it has been applied, or between two coats of paint.
| Defects | Solutions |
|---|---|
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Unsuitable stain, that inhibits the reaction of the coating (mainly polyester)
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For a more in-depth analysis, please contact our Customer Service
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Support specific features (paper impregnated with various resins, exotic woods, laminates, plastics and other special materials)
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For products formulated for specific supports, to obtain the desired results, you should follow special application instructions. Each product technical data sheet contains all the details to be followed for each specific application
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The coating is not perfectly dry (especially in the case of polyester over-coating)
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Extend drying time or increase coating temperature and ventilation (in case of tunnels)
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Inadequate sanding (adhesion to the surface is also achieved physically, through the adhesion to micro-cracks left by sandpaper. Adhesion on surfaces sanded using too thin paper is more difficult)
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Check the sanding and sanding paper type and condition
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Excessive moisture on the surface (above 14%): moisture may result either from gradual absorption of air, or from condensation of moisture after quick passage of the panels from cold to hot temperature
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Restore support moisture to normal values. In cold seasons leave the pieces to acclimatize before painting
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Sealers that are too cross-linked due to excessive catalysis, too fast reaction or addition of accelerators (too crystallized and glassy surfaces do not allow a chemical adhesion of the following coats of paint)
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Bring back the reactivity of the product to the normal conditions specified in the technical data sheets. Sand the surface with thicker sandpaper in order to achieve a physical grip
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Exceeding of maximum intervals between coats of paint and complete insolubility of the underlying coating in the over-coated one (this creates crystallized and glassy surfaces that prevent chemical adhesion of the following coats of paint)
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To avoid the lack of grip due to double layer, sand each coat of paint, to restore their physical grip. In the case of insulator, apply another coat of product and proceed to over-coating it following the correct timing
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Excessive brittleness of the chosen cycle
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See: Brittleness
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failure in a coating occurring during or after drying, in the form of a clear whitish film, which reduces or eliminates product clearness.
| Defects | Solutions |
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Presence of incompatible substances in the wood
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Sand to raw wood and re-coat, insulating with suitable insulators
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In polyurethane products bleaching may be caused by:
• damaged second component • incompatible second component • too high thickness, so part of the solvent remains enclosed • Presence of incompatible materials in the coating Failure due to incompatibility can occur either after a short time, or in the long run, according to the specific degree of incompatibility |
Sand to raw wood and re-coat
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It occurs when there is high humidity in the workplace. The problem can occur especially with nitrocellulose film-forming products, by condensation of room moisture on the panel due to the cooling of the panel itself after solvent evaporation (the more the evaporation is rapid, the higher are cooling and the chance of condensation)
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Condition the environment, use slower solvents that do not cool the film during the evaporation. Use anti-bleaching products or recoat the bleached film with a product diluted with a suitable thinner
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Early packing of the manufacture (before complete drying of the top-coat)
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Before packing, wait for the time needed for the coating to dry, as suggested in the technical sheets
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Presence of excess moisture in the wood. Presence of excess glue, incompatible with the coating product or producing substances incompatible with the coating by reaction
Air retention within the film with consequent bleaching due to the presence of myriads of micro bubbles |
Apply the product to a surface having optimum moisture level. Sand to raw wood and re-coat , isolating in advance with suitable insulators
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Air retention within the film with consequent bleaching due to the presence of myriads of micro bubbles
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Thin the product more, and delay the drying process with appropriate thinners; reduce the quantities applied
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Water in the airbrush through the compressed air line
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Check the efficiency of the moisture filters of the compressed air line
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