13 main paint defects, their causes and how to eliminate errors yourself

Painting work requires a certain experience, compliance with technological requirements for applying paints and varnishes. The appearance of defects in the paintwork is explained by non-compliance with the conditions specified in the instructions of the manufacturers, a negligent attitude to the work performed. Correcting errors will require additional effort and material costs.

Common Paint Defects

A damaged layer of paint and lacquer on a product, the panels spoil the appearance and damage the protective properties of paint materials. The main reason for errors in the work is non-compliance with the technological requirements specified in the manufacturers' instructions.

Table of possible paint defects:

Spider

Cracks appear at high humidity of the primer, at room temperature above +20 degrees, under the influence of direct sunlight.

Craters

The appearance of holes in the varnish with a diameter from a few microns to 1 millimeter.

Reasons for the appearance:

• insufficient dust removal;
• foam in the paint under stirring;
• traces of fat based.

When paint materials come into contact with rubber seals, the size of the craters increases.

Wrinkles

After drying, longitudinal or transverse tubercles form on the surface.

Reasons:

• the thickness of the paint layer exceeds the norm;
• thick paint consistency;
• the painting process was carried out under the influence of solar radiation, which caused uneven heating of the paint layer.

Violation of the rules for the preparation and painting process leads to a negative result.

Influx

Sag in the form of frozen waves is formed when painting vertical surfaces.

The problem is:

• excessive use of solvents;
• insufficient concentration of the solvent in the paint;
• apply varnish on a wet base;
• spraying paint or varnish from the wrong angle.

Increasing or decreasing the fluidity of the coloring composition also affects the quality of the surface layer.

Delamination

With this defect, the varnish exfoliates from the base layer of enamel; the enamel leaves the primer or stratifies in the thickness of the paint layer.

The cause of the lack of adhesion can be:

• the primer is applied to a surface that is not cleaned of dirt and not degreased after grinding;
• incompatibility in the composition of putty and enamel paint;
• low-quality solvent for varnish and paint;
• excessive thickness of the base layer;
• overexposure of the enamel layer before varnish application;
• wetting and dusting the base coat before applying the varnish.

The varnish is applied no later than 8 hours after the enamel layer has dried.

Cloudiness

After drying, a darker stain may appear on the enamel or varnish.

The main reason is a violation of the temperature regime and the standards for applying the coloring composition. When painting and varnishing, the temperature should not exceed +40 degrees and fall below +18. Haze occurs when the 2nd and 3rd coats of varnish are applied to a wet surface. Insufficient amount of hardener or poor mixing with enamel.

drops

Clear panels show excess hardened enamel paint. Enamel containing higher than standard thinner has low viscosity and does not set with the base coat.

The paint is applied to the surface contaminated with mechanical impurities.

Increased fluidity due to slow solvent evaporation at low ambient temperature, large nozzle diameter, cooled paint surface, subcooled spray material. Excessive pressure leaving gun tip at close range.

Inclusions

On a freshly painted surface, dust particles are visible after performing a technological operation or cleaning the part. Sources of dust include abrasives, work clothes, tools, indoor air and dirty indoor floors.

Swelling

Peel paint or varnish without compromising the integrity of the paint layer. Swells appear at the places where the vapor contained in the air settles. In some cases, the cause of the bubbles is hard water (the salts it contains). Painting primed/sealant surfaces that are not completely cured will cause water to condense on the surface.

Low hiding power

The bottom layer is visible through the top layer. The paint did not have a uniform (unmixed) consistency. Enamel was applied too thinly or unevenly. The drying period is not exceeded.

Mast

The lack of gloss of the painted surface, guaranteed by the enamel manufacturer, is a consequence of:

• excessive thickness of the coloring layer;
• high humidity in the room;
• a rapidly evaporating thinner (moisture settles on the surface);
• the pressure is higher than normal in the gun jet;
• air temperature below +18 degrees.

Enamel gloss is particularly demanding in terms of temperature control.

Risks

After drying, under a layer of paint, scratches are visible, which remain after sanding the primed surface.

Failure to adhere to a painted surface

Insufficient adhesion of the paint to the support: metal, wood, concrete. Reasons for the defect:

• the presence of condensation, dust, corrosion, traces of oil and wax on the prepared surface;
• room dust;
• overheated or overcooled surface.

To paint aluminum surfaces, special enamels are required.Before starting to repair damaged paint, it is necessary to establish the cause of the problem.

Solutions to Common Problems

The methods of eliminating faults are very similar, regardless of the cause. Minor damage is removed with a fine abrasive, for example, when wrinkles, streaks appear or the bottom layer is translucent. After grinding, the damaged area is tinted with a thin layer.

To eliminate more serious defects, a new staining cycle is necessary:

1. With a cobweb, the painted layer is peeled off with fine-grained sandpaper. dusting; colored.
2. After the appearance of craters, the paint is cleaned up to the base coat, the dust is removed, degreased and painted.
3. Removing sags is carried out with the help of sandpaper step by step:

• initial treatment with P600 grit;
• the next stage - Р1200;
• the last one is P2000. Minor deposits are removed with P1200 and P2000 abrasives.

4. When peeling, it is necessary to observe the conditions of cleanliness and temperature when applying the paint. To correct the defect, the scrub is completely cleaned, dusted, putty, primer, paint and varnish are applied.
5. The cloudy spot is removed at the base, the whole technological operation is repeated from the very beginning.
6. The area with dust inclusions is removed and repainted.
7. The bubbles are removed in a solid layer, after which the staining is repeated again.
8. Unevenness of tone in inconspicuous places is eliminated by polishing. In other cases, it is sanded and repainted according to technology.
9. To hide emerging grinding marks (scratches), remove the paint on the defective area. Grind with a finer abrasive, followed by primer and paint.
10. Violation of the adhesion of the paint to the base requires the removal of the applied coating and the repetition of the technological cycle according to the instructions.

When performing painting work, you need to be familiar with the technological process.

Prevention of paint defects

In order to avoid premature destruction of the paint, before starting the painting work, it is necessary to determine:

• which formulations are suitable for the best adhesion to the surfaces selected for painting;
• temperature fluctuations;
• exposure to moisture;
• chemical and mechanical resistance.

Consideration of the listed criteria is the basis for obtaining a beautiful and durable coating. Carelessly reading or ignoring manufacturer's instructions are the most common mistakes non-professional painters make. When painting metal structures, they forget about additional corrosion protection when preparing surfaces. On a silver metal, there is often an "apple" defect: a combination of light and dark spots. When painting, it is important to respect the pressure, the diameter of the nozzle, the temperature correspondence between the projected paint and the surface.

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