Before we can get to the “WOW” factor of any automotive paint job we need to lay the ground work. With all the types of primers it can be easy to have your head spinning trying to figure out which one is best. Today I will hopefully put your fears to rest while explaining the differences. There are really just three reasons to use primer on your next paint job. Base primer for adhesion, Primer surfacer provides a body to sand your panels laser straight, sealer to block out old colors and paint jobs.
These two pictures/hyperlinks are examples to get you familiar with the primers. Let’s start with the base to your overall paint job. You’ll want a primer to securely grip the substrates you’re painting over such as bare metal,body filler,fiberglass, etc. We have two options for this first primer, one is the Epoxy primer you see in the left picture above. This primer is a two part catalyzed product which not only lays down and grips the surface like glue for your paint job it also creates a moisture barrier. This can be a huge advantage if you need to leave your project sit in primer in the garage for some time. Nothing is worse than seeing rust forming through your primer knowing you’ll have to strip the entire project back to bare metal. You will have to mix the primer with an catalyst prior to putting in your spray gun and priming. This simply means you cannot return mixed product back to the can. A little waste always happens, in my opinion the benefits of this primer far outweigh the fact that there is a little waste. The strength of this primer allows you to actually do body filler on top of this primer. This is a HUGE advantage to the weekend warrior who might only be able to work on his/her project a little here and there. You can strip the vehicle down to bare metal, prime with Epoxy, and then do the body work as time allows. The other base primer option will be a self etching primer. Now a self etch primer is another great option which will not require you to mix a catalyst in as it is an air dry primer. This makes figuring out how much you need easy, simply fill your paint cup and return unused primer back into the can when finished. This lacquer based primer has a little bit of acid built in to really grip the surface to increase adhesion and durability of your next paint job.
After you have a base primer to lay the groundwork for the rest of your paint job it is time to put down a primer surfacer which is a high building primer. This means you’ll wind up sanding a lot of these primers back off. The purpose behind this is to allow you to get rid of those last little minor surface imperfections to allow your panels to be laser straight. This will help your final paint job look like glass. In this category of primer there are two types. The first we will talk about is a Urethane Primer Surfacer. This primer is designed to have a slight fill before your final steps of paint. This product is best applied to panels which have been sanded to 180-220 grit sand scratches. This way you get the mechanical bond without having too deep a scratch you would wind up seeing later. Now the next option for a primer will be a Polyester Primer Surfacer. These primers have extremely high build and can even be applied to a surface with sand scratches as deep as 80 grit. Polyester primers are gaining popularity to allow the user to get a start to a straight panel on their over all project, and then come back with urethane primer surfacer to put the finishing touches on.
The last type of primer to talk about today is sealer. With the Eastwood line of paints we don’t have a stand alone sealer to add to confusion. We simply recommend reducing our Epoxy primer with Universal Urethane reducer up to 20%. A sealer doesn’t need quite as much of a build as a base primer so reducing is perfect. The biggest use for a sealer would be if you simply want to change the color of your vehicle, especially when that color change is drastic such as going from a dark to light color. You can simply sand the existing paint with 400 grit sand paper to prepare and then lay down 1-2 coats of sealer to achieve desired coverage. From here you’re ready to move to the color and clear.
We hope this helps set your mind at ease when the time comes to prime your next project. The more time you take to prep and sand and check your work the better your overall paint job will come out.