What to do?

You have encountered a problem when applying paint ? Some brands appear on the painted surface ? Wondering what steps you missed ?

Here are the tips from our professionals in industrial painting at Peintures PMS related to small problems that can occur during any stage of the application of the paint.

Overspray

DESCRIPTION
Sandy appearance of the film due to the overspray fallen on the freshly sprayed surface and no
longer absorbed.

CAUSES
The small paint particles settle on the wet film due to:
• Inadequate masking of the substrate.
• Insufficient ventilation in the spray booth.- Poor spray gun technique (f.i. too high spray pressure).
• Too fast drying products (too fast thinner used).

REMEDY
In most cases, polishing is sufficient.

PREVENTION
• Mask accurately the surface to be protected, especially on the edges.
• Follow the application techniques as indicated in the data-sheet.
• Check the air flow in the spray booth.

Bleeding

DESCRIPTION
Evident stain due to a soluble dyestuff.

CAUSES
• Use of soluble pigments.
• Reaction of the putty’s peroxides with dyestuffs or pigments present in the paint film.
• Bitumen or tar residues.

REMEDY
Insulate the damaged parts. In particularly serious cases sand until bare metal and restart the correct
paint process.

PREVENTION
• Effect the solvent test to verify the possible presence of soluble dyestuffs.
• Verify the correct putty’s hardener and peroxide dosage.
• Ensure that all possible tar or bitumen residues have been removed.

Gloss Difference – Sinkage

DESCRIPTION
Some points of the painted surface present insufficient gloss.

CAUSES
• Insufficient drying time of the undercoats.
• Use of too aggressive thinners.
• Use of inappropriate hardeners.
• Too slow drying depending on excessive humidity.
• Insufficient recirculated air in the oven during the drying process.
• Contact of the film not yet dried through with weather aggressives and/or chemical aggressives.

REMEDY
After through drying of the film:
• Polish using an abrasive compound according to the degree of gloss.
• If polishing does not restore the gloss, flat with abrasive paper, then re-spray.

PREVENTION
• Alwais follow the data-sheet prescriptions, apply the undercoats in the suggested film thickness, allowing adequate drying time between all coats.
• Respect the baking temperatures for undercoats and finishing coat, in well aerated oven, expecially in case of low room temperature and high humidity.
• Avoid to expose the painted surface to any aggressive in the first days after the painting.

Bubbles in general

DESCRIPTION
Bubble-shaped irregular swellings.BUBBLES
– Due to corrosion.
– Due to drying.
– Due to air trapping.

CAUSES
Due to corrosion:
• Mechanical damages on the painted surface with subsequent humidity infiltration.
• Insufficient preliminary substrate pre-treatment or incomplete anti-rust substrate treatment.
• Rust formation on sanded or dismantled surfaces.
• Insufficient box sealing. Due to drying:
o High film thickness.
o Too fast hardeners and thinners.
o Short flash-off.
o Too high IR temperature.
o Too short flash-off in wet-on-wet process. Due to air trapping:
• Insufficient putty or priming coat application.
• Insufficient thinning of the scaled film edges.
• Air pockets in the priming coat due to unsuitable thinner.
• High drying temperature.

REMEDY
Sand until underlying layers by removing bubbles and/or rust. If necessary, apply an anticorrosive primer as soon as possible in order to avoid further corrosion phenomena.

Rusting

DESCRIPTION
The paint system has been forced up because of rust present on the steel substrate.

CAUSES
• Attack of the metal surface depending on contact with aggressives, generally due to a damage of the paint film.
• Presence of humidity on the metallic surface before applying the anti-corrosive primer.

REMEDY
Sand the rusted part carefully until bare metal, sand the steel sheet by removing all rust, clean the metal substrate by means of suitable detergents and then repeat the process starting from the anticorrosive primer.

PREVENTION
• Repair the damaged points of the paint film as soon as possible.
• Clean accurately the metallic surface, dry it with clean cloths, and apply a suitable anti-corrosive primer not later than 30 mins.

Removing of original coatings

DESCRIPTION
Some points of the finishing present more or less wrinkling.

CAUSES
The original film was attacked by the solvents due to:
• The original painting was a thermoplastic or powder type(normally used by the car manufacturers).
• The original painting (solvent or water based type) was not enough dried.

Chiaroscuro Haloes

DESCRIPTION
The surface presents different colour shades (edges, lower panels).

CAUSES
• Poor hiding power, depending on insufficient film thickness due to:
o Not suitable application technique, especially in the less accessible points.
o Too few coats applied.
o Low coverage shade that needs a specific coloured undercoat.
o Overthinning, and/or incorrect mixing ratio.
• Too short flash-off between coats or before the clearcoat application.
• Thick or thin basecoat application.

REMEDY
• Sand slightly and recoat.
• If the haloes appear by spraying, spray in a uniform way.

PREVENTION
• Use appropriate application techniques to reach a correct film thickness on the whole surface.
• Apply a coats-number as indicated in the data sheet.
• Always control if the finishing coat needs a coloured underground: if the case always apply the specific coloured undercoat.
• Always stir paint thoroughly and filter it before application.

Cissing, Cratering, Fish-Eyes

DESCRIPTION
Paint repelled by contaminant forms craters like depressions with relief edges. Inspection with lens may reveal a small impurity at the base.

CAUSES
• Incorrect use of antistatic clean cloths, that can contaminate the substrate.
• The spray booth and/or the substrate are contaminated with silicone.
• Contaminated compressed air (presence of water, oil, grease, wax).
• Solvent contaminated spray gun when using water-borne products.

REMEDY
Allow the film to harden:
• Remove by sanding the affected paint, clean accurately and re-spray.
• If the paint still forms craters, add a specific anti-silicone to it.

PREVENTION
• Clean and degrease the substrate thoroughly before spraying the nex coat, using specific ANTI-SILICONE solvent. Remove the solvent with clean cloths before it can dry.
• Check the spray booth filters and the oil/water separator and drain if necessary.
• Alwais check the surface before spraying next coats; if necessary operate as indicated above.
• Use only spray equipments perfectly clean.
• Don’t use products containing silicone in the spray booth.
• Clean with suitable solvents and allow spray guns to dry when using water-borne products.

Sanding Marks

DESCRIPTION
Fine scratches can be seen in the top coat.

CAUSES
• The sanding grade was too coarse for the product subsequently applied.
• Final sanding with too fine sand paper after previously sanding with coarse sand paper (f.i. P180 than P360).
• The primer or filler was not sufficiently through-hardened for sanding.
• Insufficient film thickness.

REMEDY
• After it has thorough hardened, sand the top coat smooth with fine sand paper and polish.
• If the surface shows serious marks sand thoroughly and reapply the topcoat and the sealer if necessary.

PREVENTION
• Consult the data sheet for the substrates (putty and filler) and choose the correct sanding grade.
• Using different grades of sand paper follow the prescriptions of the data sheet and of the producer of abrasive papers.
• Always let dry through the substrate before sanding (see data sheet).
• Apply the top coat in correct film thickness.

Colour Difference

DESCRIPTION
The colour shade of the repaired area does not match the car’s original colour.

CAUSES
• Original car finish does not correspond with the mixed colour.
• The mixed colour was obtained using pigments different from the original ones: metamerism.
• Mixing colours have not been stirred enough.
• Irregular spraying technique (number of coats, gun’s adjustment).
• The spray check was carried out in incorrect light.
• The test panel was sprayed incorrectly.

REMEDY
After through drying of the film:
• Sand the repaired section, mix the colour again, compare a test panel and re-apply the colour.

PREVENTION
• Use correctly the colormap and the other helps offered by the Color-System.
• In any case, before painting the substrate, always spray with the same spray gun as of the final application a test panel using the correctly catalysed and thinned product, with the same spray gun of the final painting and the same spray technique. Check the colour under different visual angles and different light sources.
• Use the recommended prescriptions indicated in the data sheet.
• Always mix accurately the paint and filter it before spraying.
• Mix the paint carefully and always filter before applying it, by using compatible filters (in the spray gun too) with the aluminium particles size.

Pin Holing

Small deep holes in the paint surface: observing accurately one can see the paint layer in which the hole originated (sealer or putty).

CAUSES
Penetration of the final coat into the holes due to air trapped in the film:
• Incorrect application of the filler (sanding, sealing, a. s. o.)
• Too fast drying (oven or IR lamps) of the filler applied in too thick layer.
• Insufficient filling technique and sanding of the putty (hollows emerge).

REMEDY
After the complete drying through of the film:
• Sand the paint or filler completely to remove the pinholes; apply a suitable sealer filler, sand accurately and re-apply the final coat.

PREVENTION
• Follow the prescriptions of the data sheet, respect the thickness of the layer and allow the correct flash off and drying times.
• Apply the putty in subsequent thin layers to avoid trapping air in the mass.
• Always check the substrate before applying the top coat and, if necessary, operate as indicated above.

Pores in the filler

DESCRIPTION
The film shows more small holes.

CAUSES
Incorrect application of the filler-sealer due to:
• Application of the filler at too high viscosity or use of inappropriate thinner.
• Application in too thick layer.
• Use of too fast hardeners especially in summer.
• Filler drying in the direct sun rays.

REMEDY
After through drying of the film:
• Sand thoroughly and re-spray the filler-sealer.

PREVENTION
• Observe the prescriptions of the data sheet: apply the fillersealer in the suggested film thickness, respect the flash off time between the coats and let dry correctly.
• Check the spray viscosity before applying.
• Use the suggested hardeners and thinners, depending on the ambient temperature.
• Allow to dry inside the body shop or in areas that do not allow a direct contact with sun rays.

Bleeding Yellowish Stains

DESCRIPTION
The freshly-applied top coat shows local discoloration and/or yellowing in the points previously treated with polyester putty.

CAUSES
Too much hardener (peroxide) added to polyester putty.

REMEDY
After the film is fully hardened:
• Sand thoroughly to the surface of the putty. Apply a sealer and re-spray the final coat.

PREVENTION
• Use the correct mixing ratios (showed in the data sheet), and mix the components in the correct way into an homogeneous mass.
• Use the dispenser measuring correctly the mixing ratios, or operate by weight with the scale.

Water Markings and Spotting

DESCRIPTION
The edge of evaporated water droplets can be seen on the paint film.

CAUSES
When water dropped on the paint surface and evaporate(especially on horizontal surfaces) the outline of the drop may still be seen. It depends on the fact that the paint coat has been exposed to rain or water drops while it was cooling.

REMEDY
Let dry through the film, then:
• Sand and polish.
• If repeated polishing are not effective, sand the affected area and re-spray.

PREVENTION
• Protect the car immediately after the painting and avoid contact with water before it is fully hardened.

Blistering

DESCRIPTION
The painted surface displays more or less small pimples.

CAUSES
Blistering is caused by moisture or contamination under the paint film due to:
• Moisture absorption by the underground (putty and sealer) before the application of the finishing coat.
• Moisture condensation on the substrate f.i. depending on a sudden change in temperature (e.g. the hot car out of the oven).
• Contamination of the substrate by water, grease, oils, a.s.o.
• Use of non compatible products (f.i. not suitable or contaminated thinners).
• The painted surface, before the complete through hardening of the film, was exposed to an high level of moisture or rain.
• Thinning of water-borne product with tap water (contains mineral salts).

REMEDY
After drying through of the film control the depth of the pimples:
• If these are between the final coat and the underground, sand to reach a completely smooth surface, then re-coat.
• If the pimples are between the substrate and the undercoat, sand thoroughly, clean accurately and repeat the complete paint system.

PREVENTION
• Ensure the surface is thoroughly cleaned before any operation(use compressed air and silicon remover degreaser)
• Protect the surface before the paint application and immediately after, to avoid moisture condensation.
• Use experimented paint cycles to avoid any incompatibility.
• Control the compressed air supply to eliminate any trace of oil, fat or water.
• After wet sanding allow water to evaporate.
• Dry-sand only polyester putties.

Metallic Impurities

DESCRIPTION
Some aluminium particles appear in vertical orientation in the finishing coat.

CAUSES
Application conditions of a metallic matt base coat may be inappropriate, f.i.:
• Poor spray gun technique (f.i. dry spray). Inadequate stirring and filtering of the paint.
• Use of inappropriate spray gun (spray nozzle, air pressure) and/or spray gun held too far from surface.
• Film thickness of the clear insufficient to cover the aluminium flakes (expecially with “magnum size” coarse particles).

REMEDY
After through drying of the clear: sand with P800 grit paper and apply a new coat of clear.

PREVENTION
• Always follow the prescriptions of the data sheet and use the indicated spray techniques.
• Check the adjustment of the spray gun (nozzle, yield, air pressure).
• In touch-ups or complete paint use specific “blenders”.

Stone Impact Split

DESCRIPTION
Deep paint film damage due to external agents.

CAUSES
Violent impact provoked by rebound on the steel sheet of blunt instruments (stones, pebbles, various sharpened objects).

REMEDY
Sand the damaged zone, apply putty if necessary and then repaint.

PREVENTION
Being this phenomenon independent of the human behaviour, only a special attention is required when you meet critical situations of soil, not asphalted roads, little cleaned environments, etc.

Peeling – Flaking

DESCRIPTION
Small or large areas of a layer detaches itself from the substrate or from previous layer.

CAUSES
The paint film is stressed by forces that oppose to the adhesion. Loss of adhesion due to:
• Presence of wax, fat, silicone, oil, detaching agents.
• Inadequate coupling of the surface.
• Unsuitable superficial temperature during application.
• Incorrect film thickness.

REMEDY
Remove loose paint layers and re-apply the system.

PREVENTION
• Check accurately the substrate and choose a suitable paint system.
• Pre-treat suitably the substrate. Consider that sanding and sand-blasting increasing the contact surface improve the adhesion.
• Degrease accurately to remove any contamination that can reduce the wetting of the substrate by the new coat.
• Check the spray viscosity: lower viscosity increase the wetting of the substrate and improve the adhesion.
• Observe the flash-off time indicated in the data sheet between the layers of the paint system.
• In two-coats system (basecoat + clear) the oven drying improves a better adhesion between the coats.
• Avoid “mixed” cycles by using products of different paint manufacturers.

Polishing Marks

DESCRIPTION
Some spots more or less glossy, generally round, on the finishing coat.

CAUSES
The surface of the paint film has been abraded depending on:
• Unsuitable polishing techniques (speed, pressure) or used materials (rubbing compound, plug).
• Paint film not yet through hardened.

REMEDY
After through hardening of the film:
• Repeat the polishing operations.
• If necessary sand slightly and re-paint.

PREVENTION
• Use specific polishing techniques and materials depending on the finishing coat.
• Let dry perfectly the paint film before polishing it.

Craters on the undercoat

DESCRIPTION
Small holes on the surface of the undercoat.

CAUSES
• Incorrect use of antistatic clean cloths, that can contaminate the undercoat surface.
• The spray booth and/or the surface to be painted are contaminated with silicone.
• Contaminated compressed air (presence of water, oil, wax).
• Solvent contaminated spray gun when using water-borne products.

REMEDY
After the through drying of the film:
• Sand the cratered paint coat to eliminate any defect. Clean and degrease thoroughly with anti-silicone solvent, then apply a new coat.

PREVENTION
• Degrease the substrate thoroughly before spraying, using the specific “ANTISILICONE” solvent. Remove the solvent with clean cloths before it can dry.
• Check the spray booth filters and the oil/water separator and drain if necessary.
• Alwais check the surface before spraying next coats; if necessary operate as indicated above.
• Clean with suitable solvents and allow spray guns to dry when using water-borne products.

Orange Peel

DESCRIPTION
The painted surface presents poor flow and resembles orange peel.

CAUSES
Poor flow due to:
• Poor spray gun technique (gun held too far from the surface, too dry spraying).
• Unsuitable spray gun (spray nozzle, air pressure, etc).
• Spray viscosity too high.
• Use of too fast or unsuitable thinner.
• Too short flash off between the coats.
• Surface and/or spray booth temperature too high.
• Application of excessively thick or thin films.

REMEDY
After the paint is thoroughly hardened:
• Rub out orange peel with very fine abrasive paper and polish.
• In severe case flat thoroughly and re-spray.

PREVENTION
• Alwais follow the data-sheet prescriptions and observe the suggested spray gun techniques.
• Use the suggested thinners depending on the room conditions, check the spray viscosity and the
air pressure.
• Apply uniform coats and respect the flash off time between the coats.
• Check the room conditions: temperature and ventilation.

Wrinkling

DESCRIPTION
The paint surface acquires a finely waved appearance.

CAUSES
• Paint applied to a solvent sensitive and/or only partially dry substrate, without previous application of a suitable sealer.
• Use of too aggressive or inappropriate thinner.
• Use of sealers not suitable for the old film.
• In case of two-coats finishes, partial removal of the clear by sanding, without correct sealing.
• Too high film thickness.

REMEDY
After trough drying of the film: – For a slightly wrinkled surface sand with fine sand paper and re-spray. If the surface shows serious signs of wrinkling, remove thoroughly the paint and apply once more.

PREVENTION
• Ensure that the substrate is not sensitive to the solvents and has through hardened. If the case seal completely with a suitable sealer (f.i. water thinnable sealer).
• To sensitive substrates it is possible to apply a two components sealer in very thin coats, allowing long flash off times between the coats.
• Use only the prescribed hardeners and thinners.

Popping

DESCRIPTION
Bubbles (closed or partially opened) trapped during the application of the paint, being unable to escape because of quick film set up.

CAUSES
Air or solvent vapours trapped in the film, due to:
• Viscosity too high. Use of cheap thinner.
• Thinner too fast (especially in summer).
• Inappropriate use of fast hardeners.
• Application of excessively thick films or too short flash-off time between the coats.
• Ambient temperature too high, heating sources too near, too short flash-off time.
• The painted car was exposed directly in the sun immediately after the application of the final coat.
• Incorrect drying time before baking (for water-borne clear coats).

REMEDY
After drying through of the film.
• Sand to obtain a smooth surface and re-spray.

PREVENTION
• Always follow the data-sheet prescriptions before applying undercoats or finishing coats.
• Use the suggested thinners and hardeners depending on the room temperature.
• Ensure spray viscosity is correct.
• Observe the flash-off times between the coats and the dry time after the final coat.
• Control the oven temperature and/or the distance of the IR lamps.
• Check at regular intervals the oven temperature control gear.
• For waterborne products follow flash-off times before baking.

Water Bubbles

DESCRIPTION
Marks of evaporated water droplets can be seen on the painted surface.

CAUSES
Traces of water under the film, due to:
• Residual water in case of wet sanding.
• Water in the line of compressed air supply.
• Contact of the paint film with rain or with sprinklings of water.
• Not evaporated water from the water-borne basecoat and/or filler.

REMEDY
After drying through of the film:
• Sand the surface and polish it.
• In case of deep defects, sand thoroughly and repaint.

PREVENTION
• Clean always the surface thoroughly (compressed air and silicon remover degreaser).
• Control the compressed air supply to eliminate any trace of water.
• Respect correct drying times recommended on the technical data sheet according to temperature and relative humidity.

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