This is a down and dirty explanation hope it helps.

Always try to stay within a system. Read the tech sheets on the products you are looking to use. Always do a spray out to check color. And take a trial run before painting the real deal. When all else fails ask the distributor, call a tech line for the paint company or try to contact the local rep.

Etch or wash primers – Go direct to bare metal and assist in adhesion but are mostly there to serve as a conversion coating to prevent a rock chip from getting out of control. Do not put over filler. Do not put filler over.

Epoxies – Can go direct to metal and work well by themselves. There is debate as to weather it is best to put over an etch or not, personal preference and experience. I have done both ways with success. Can go over body filler and body filler can go over epoxies once the epoxy is properly prepped. Epoxies can also be used as a sealer. That said you can put urethane primers over them or under them and color can also be put directly on them as well. Watch your dry times epoxies are slow. Epoxies also have little filling capability but with a couple of coats they can prevent corrosion quite well.

Urethane Primers – Must have a etch or epoxy under them except for small (quarter or style line) cut troughs. Some companies recommend a sealer some don’t so follow manufacturer recommendations.
They can go directly over body filler (180 is the coarsest grit scratch I am aware of) but body filler should not be put over them (some glazing putties are okay). They will not prevent moisture from saturating through to metal so don’t put a car outside and allow it to soak wet sanding is okay. Also they are not body filler!!! 3 coats let it dry and sand it add more if necessary and watch flash times. A good filler primer builds 4-6 mils a crisp dollar bill is 2 mils thick and new OEM paint jobs are an average of 4-6 total.

*DO NOT USE LAQUER PRIMERS!!!

Sealers – Some companies do not require. They will fill at most a 320 grit scratch. They are meant to go over primer and cover very very small cut throughs (to metal or filler) and help with the porosity of primers for better color hold out. It also makes for a uniform color to go over resulting in faster hiding and better color uniformity. Some companies use colored sealers and some use various shades of grey and both work.

From here on all you have to do is pick a color and decide if you want to spray basecoat clear coat or single stage!

Also make sure to wear your Personal Protective Equipment!

Good luck.


Geno