PAINT PROBLEMS - A QUICK GUIDE IN IDENTIFYING AND SOLVING.

Dec 5, 2016
3 min read

Contrary to popular belief, there is a lot to painting a vehicle than just mixing the paint and application. There is a lot of work that goes into each and every project to get to the desired finish and look and there is also a lot of things that could go wrong.

In the following, I will try and outlay some of the problems you can face and how to fix them.

KNOWING YOUR SOLVENTS, HARDENERS AND MIX RATIONS

SOLVENTS

Standard laquer thinners - Cleaning of spray guns, nozzles etc - Use as much as needed to get it right
Grade Ä" laquer thinners - Used with Nitro Cellulose (1k) - 35% - 50% average percentage
QD Thinners - Use with QD paint - 30% - 50% average percentage
2K thinners - Use with 2k primers and 2k paint - 10% - 30% average percentage
Basecoat thinners - Use with basecoat - 10% - 20% average percentage

HARDENERS

MS slow hardener
MS hardener
MS hardener fast
Hardener slow
Hardener medium
Hardener fast
Hardener extra fast

All these can be used in conjunction with 2k or clear coat , mix ratio of 2-1 with 10% thinners

Misuse or using the wrong hardener can cause the colour to change to a yellowish colour and also the paint will not cure. This is different to drying, it may feel dry, but it does not mean that it is cured.

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FISH EYES/SILICONE/CRATERS

These appear on the surface as small circular indentations ranging in diameter from 0.5mm to 3-4mm. They can vary in appearance from a very flat recess in the top coat to a very deep fault which extends into the substrate. If correctly repaired, these craters may reappear as a flat recess.

WHY IT HAPPENS

The most common causes are - oil, wax and silicone residue. These can be deposited on the vehicle via -

clothing, dirty rags etc.
Dirty/faulty airlines
Wrong water traps
Release agents from new cloths and sponges
Polluted air in the workplace

HOW TO STOP IT

Use only silicone products
Make sure the substrates are correctly cleaned in readiness for paint
Make sure all equipment is ready and in good working order.

HOW TO REPAIR IT

This can be done by thoroughly sanding down the area and polishing back up, or if this does not work, you will have to repaint. Be very careful when attempting to sand and polish fresh paint.

EXAMPLES

LIFTING/WRINKLING

Sometimes after painting a vehicle, various defects such as - shrinkage, wrinkling or swelling can occur. This can vary in severity.

WHY IT HAPPENS

Inconsistent drying inside the paint film.
Inadequate drying time between coats and forced drying.
The use of the wrong solvents or poor quality solvents.

HOW TO STOP IT

Paint application - thin even coats
Always use the correct amount of time for drying between coats and also ensure that the temperature is correct.
Use the correct solvents

HOW TO REPAIR IT

Allow the film to harden thoroughly. If the defects are slight you can try rubbing down and polishing the area. If this does not work or in severe cases you will need to rub down to the substrate and re paint.

EXAMPLES

ORANGE PEEL

This is when there is poor surface texture of the paint, it resembles the surface texture of an orange - hence the term "orange Peel".

WHY IT HAPPENS

Inaccurate spraying pressure/ viscosity, spraying technique and application temperature
Wrong solvents or the use of cheap solvents
Sanding of the substrate not done sufficiently
Spray guns not set up correctly