Many painting defects are not caused by product quality, but by surface preparation, equipment adjustment, and application technique. For a workshop, these mistakes mean wasted material, lost time redoing the work, and sometimes, dissatisfied customers. Here are the five most common errors in spray painting and how they can be prevented.

1. Insufficient surface preparation

Applying paint to an insufficiently cleaned, degreased, or sanded surface is one of the main causes of adhesion problems. Residues of silicone, grease, dust, or rust can cause paint flaking, blistering, or cratering.

The surface must be properly cleaned, degreased, and sanded before product application. Dust resulting from sanding must be completely removed, and exposed metal areas must be treated with the recommended products for the painting system used.

2. Incorrect gun adjustment

Air pressure, material flow, and spray pattern directly influence application quality. Too much pressure can cause excessive overspray and material loss, while too little pressure can lead to improper atomization and an uneven finish.

The gun must be adjusted according to the product, the nozzle used, and the manufacturer's recommendations. Before painting the part, it is advisable to perform a spray test to check the spray pattern and the amount of material applied.

3. Improper application distance or movement

Holding the gun too close to the surface promotes excessive material buildup and runs. If the gun is held too far away, the product may reach the part partially dry, resulting in a rough surface or a dry spray appearance.

The gun must be held at a constant distance and perpendicular to the surface. Movements must be uniform, and successive passes should overlap in the recommended proportion for the product being applied. The travel speed must be kept constant across the entire surface.

4. Incorrect product mixing or preparation

Failure to observe the proportions between paint, hardener, and thinner can alter the viscosity, drying time, and resistance of the final coat. Also, using an insufficiently homogenized or unfiltered product can cause shade differences, impurities, and finishing defects.

The components must be measured according to the technical data sheet, then mixed and filtered before being put into the gun. Both the induction time, if provided, and the pot life of the mixture after preparation must be observed.

5. Applying too thick coats or not respecting flash-off times

Applying too much material in a single pass increases the risk of runs, boiling, wrinkling, and uneven drying. Failure to observe flash-off times between coats can trap solvents in the film and affect the appearance and durability of the finish.

It is recommended to apply several controlled coats, observing the flash-off times indicated by the manufacturer. Temperature, humidity, and ventilation in the work area should also be checked and maintained within recommended limits.

Conclusion: how to reduce these errors at the workshop level

Most problems can be prevented through a well-established work process:

• using a checklist for cleaning, degreasing, and sanding;

• selecting the nozzle and adjusting the pressure according to the product;

• checking the spray pattern before application;

• observing mixing proportions and filtering the product;

• maintaining a constant application distance and speed;

• observing the number of coats and flash-off times;

• checking the complete painting system: primer, basecoat, clearcoat, hardener, and thinner.

Following these steps reduces unnecessary material consumption, limits rework, and contributes to obtaining a uniform and durable finish.