DuPont advises on avoiding common paint defects

When it comes to paint repairs, bodyshops always strive for perfection. However, sometimes despite the refinishers’ best efforts or due to the pressurised environment of busy bodyshops, corners may get cut and defects can occur. These are costly and time-consuming for bodyshops to rectify, so it is essential to avoid them happening in the first place.

There are seven main areas in the refinishing process where pitfalls can trip up refinishers and cause paint defects.

Cleaning

The first step of the repair process is arguably the most important in the perfect repair. It is at this stage where many paint defects are born, including blistering, lifting and peeling. Thankfully, preventing these defects is simple: proper substrate cleaning. Refinishers must ensure the surface is cleaned and de-greased completely with the right products; paint application should be carried out as soon as the substrate has been cleaned.

Surface preparation

A multitude of defects can be triggered if the surface of the repair is not prepared properly. Areas here to watch out for include not sanding the repair area enough or using the incorrect grade of sand-paper. Similarly not completing the undercoat process correctly or not allowing the undercoat to dry thoroughly will lead to many common paint defects.

Preparation of product

Once refinishers are in the mixing room there are many pitfalls waiting for them. It is essential that only recommended ancillary products, such as thinners, additives and activators, are used; using non-recommended ones is a sure-fire recipe for defects occurring later. And even if recommended products are used, they must be suitable for the bodyshop’s conditions. Technical data sheets and label instructions are there to help the refinisher so it is imperative they are followed carefully.

Application

Training is key for this stage of the repair, and there are many obvious mistakes that can happen in the spraybooth that can lead to costly defects in the finish. The basic spraygun set-up is the first thing to check. Once the application is underway, refinishers must ensure they position themselves the correct distance from the panel, apply the right number of coats, and demonstrate the relevant spraying technique for the job. Coats that are too thick, that have not had enough film build or that have not been allowed to flash-off for the correct amount of time will always cause defects.

Drying

This stage seems straightforward enough, but it is one where defects can be introduced too. The temperature of the baking cycle must be calculated according to the technical data sheet instructions – not too high and not too low but also the recommended length of time for the activator used. It is also important to respect flash-off times after the last coat was applied.

Equipment

Even if all the steps in the process are carried out flawlessly, defects can still appear. Bodyshop equipment is often the culprit, so it is very important it is maintained regularly and working perfectly. Items that can be particularly problematic include filters, pipelines and sprayguns.

Environment

In addition to the equipment posing problems, the general environment also plays a role in causing paint defects. The humidity level is a key point that refinishers should be aware of, as well as the bodyshop temperature.

In some cases the overall pollution level due to the bodyshop’s proximity to factories, for example, can impact a repair.

Anthony Cashel, brand marketing coordinator, DuPont Refinish UK and Ireland says:  “The bodyshop is littered with pitfalls for the refinisher. In order to ensure the perfect repair every time coupled with maximum productivity, refinishers must be aware of the areas that can cause paint defects. To stay up-to-date, training is key, which is why we suggest regular courses at the Refinish Training Centre in Stevenage.”