When painting certain metals you will need to use a self-etching primer. Many people would then think they would be able to paint straight over this primer, I mean, after all, you have just primed it, right?
Can You Paint Straight Over Etch Primer?
No, many self etch primers require another layer of primer to be applied on top of them before they can be painted. Not all do however and some can be painted straight over. To see whether you can you need to read the manufacturers instructions.
What Is Self Etching Primer?
Self-etching primer is a specialist primer used on bare metals. As the name suggests this primer etches into the metal, forming a really strong adhesion. Etch primers contain an acid which is what helps them to etch into the surface of the metal. Some self etch primers contain more acid than others, this is one of the conditions that can lead to another primer or sealer having to be applied on top of the self etch layer.
Painting over Self Etch primer
The best advice I can give when it comes to painting over etched primer is to simply follow the manufacturer’s instructions. Some say they can be directly painted over while others say they cannot. See what it says on your can or tin and follow those instructions, after all the manufacture knows their own paint better than anyone else.
If you do paint over with another primer then a urethane primer works well. This acts as a sealer over the self etch primer and stops any of the acids from leeching into your topcoat. This is one of the common issues with painting over self etch primers and it can lead to the topcoat completely failing.
Once you have a urethane primer on top of the self etch it can be finished with pretty much anything.
This etch primer from U-Pol can be painted straight over. Under normal circumstances, it is not necessary to flat Powercan Etch Primer and can be directly overcoated. Powercan Etch Primer may be overcoated directly with a topcoat. However, if the repair requires additional build, primer filler should be used before the topcoat is applied.
if you are using self-etching primers for the first time then you need to be aware of how dangerous they are. These kinds of paints can cause a lot of damage to your lungs so always wear a properly fitted respirator when using them. They also contain an acid so glove up!