Home Projects News and info Contact About me
Logo!

Spray painting - Paints

Primers



Paints

Deciding which paint to use is usually dictated by the job at hand, sometimes local laws make it impossible to use some kind of paint. Let's make an overview.




Primers.


There are 3 main primers on the market with their own restrictions / possibilities. On top of that there are other products which will also prime surfaces to be painted. Let's start with the most common three.

Primer: Description / Used on:

Etch primer Bare metal ready to paint, it has to be free of rust, grease and other contaminations like all other surfaces you're going to paint. Can also be applied to alumin(i)um, steel, galvanized steel, old paint layers and body filler. Best is to apply it to bare metal. It's a 1 component primer which cannot be sanded. It's not suitable to put body filler over it. Typically used on spots you sanded through to the bare metal doing the final prep (block sanding) for paint. Don't use it when the body is sandblasted and you still need to work on it.

Epoxy primer Bare metal which still needs to be to worked on, typically used on sand or soda blasted surfaces. It's a 2 component primer working with a catalyst (hardener). You can dilute it with appropriate thinners in a ratio of 5 to 10%. Works very well on bare metal and does seal the bare metal up. You can sand it, put body filler over it and it will protect the metal from rusting for a long time. Even if you let it sit for months.

High build primer / Filler You can apply it over epoxy primer, body filler and old paint. It's actually a primer which allows you to block it out to get a perfect surface before the color and clear coat goes on. Apply it in 3 medium layers to build it up and get something to work with. In general it's a 1:4 mix with hardener, it's recommended you use the appropriate hardener for it. If it's cold in your garage or workshop you may dilute it with 5 to 10% lacquer thinners as well. This stuff is made for block sanding, if ever you sand through it to the bare metal, etch-primer is the way to go to cover the bare spot(s). Do not sand the etch primer afterwards, the prepped panel is ready for paint if there are no more dents in it. If there are, go back to the previous step and apply epoxy primer before repairing the dents.

That was some text, this site won't be what it is without pictures! So, what do I use?

To start with etch primer, the picture below also shows "Barcoat" which is an isolator. I'll be discussing that in a minute. Note the Russian and French text on the can of the etch primer, in most cases it means it's not allowed to use in some parts of the world. It is also stated on the can it's acid so the utmost personal protection using this stuff is mandatory! Gloves, protective glasses and a good (gas)mask will keep you alive.

In general, if you can get it, great! Don't be disappointed your local laws forbid the use of this primer. Epoxy primer will do the job as well, it's not the same but it will work just great.

If you can get your hands on it use it on bare metal, doesn't matter if it's a body-panel which is sand of soda blasted or just a small area you sanded through to the bare metal just before putting the color and clear coat on.

Sprayguns



While we're at it, the U-POL Barcoat can be used as primer as well. It's not meant to be but it does isolate the surfaces underneath from having any effects on the paint you put over it. Normally it's used on old paints of which you don't know what it's based on. For example, you got a paint repair on your car performed with a spray-can based on acrylics or enamel and now you want to spray polyurethane paint over it, it may react to each other making it necessary to sand it all off and start from the beginning. To prevent whatever interaction with old paint, use an isolator paint like Barcoat. It's not as much a primer but on the other hand it acts like one.

Epoxy primer I don't have yet, it's on order. Since I don't want to "steal" pictures from other sites you'll have to wait for it to arrive. I'll update this page when I got it.

What I do have and use is high build primer / filler.

Sprayguns



I ordered the dark grey version of it but it turns out being quite light. It's grey alright but not as dark as I expected it to be.

Sprayguns



Spraying dark colors over a bright primer is actually an advantage, if the color coat didn't fully cover the primer it will show. Don't do it the other way around, using dark primer while the car or panel has to be painted white. You'll be needing a lot more paint to get a dark color covered.


Last update : November 23th, 2018