Where and When Do I Use Epoxy Primer on My Project?
In the past, self-etching primer was the go-to coating to apply over bare metal on a car. Metal requires little prep work to apply it, the primer flashes/dries quickly and it came in 1K aerosol cans for small jobs. However, in the past 5-10 years, you’ve probably been hearing more people talk about epoxy primers and their use for auto painting as opposed to self-etching primer.
But why use an epoxy primer? And what is it, anyway? This non-porous, high-bonding sealer has several advantages when used for certain materials and situations. However, you must be careful about what you apply it to if you want to get its full benefits. We decided to give you some insight on where and when epoxy primer works best. Here are six instances of when to use epoxy primer for great results.
1. Over Bare, Clean Metal — Epoxy primers are amazing at sealing up bare metal and not allowing moisture or corrosion to creep in. Epoxy primer seals out the oxygen from the metal along with moisture, chemicals and UV rays. This leaves no chance of rust or corrosion forming on the surface like some cheap spray bomb-type primers. Etch primer included, epoxy primer is about the only bare metal primer you could leave a vehicle outside in without rust forming back under the primer quickly! Two-part epoxy primers go one step further by including zinc phosphate, which increases its corrosion-inhibiting properties. Simply put, epoxy is the best primer for bare metal, making it excellent for newly fabricated metal parts or ones that have been fully stripped.
2. Mixed Surfaces — Some primers and coatings need the entire surface to be uniform and all the same material. Epoxy primers have excellent adhesion properties and will stick to bare metal, paints, primers and fillers. This means you can hit an area with epoxy primer that’s been sanded down to bare metal, repaired with body filler, and then feathered into the original paint. We suggest blending these areas as well as possible before spraying epoxy primers. While they do have good filling/build qualities, they aren’t quite at the level of a high-build polyester primer and won’t hide imperfections as well. Alternatively, you can apply filler or primer surfacer over the epoxy to fill any minor imperfections and block flat before you paint.
3. Stacking Coatings — Since epoxy primers adhere mechanically, they will grab onto most anything that has a good texture to the surface. For this reason, it works well for stacking if you need to correct an area that you didn’t get perfectly flat and need a little more filler. Just abrade with sandpaper, apply your filler, sand flat and feather the edges. Then you can apply more epoxy primer over top and repeat as needed. This can’t be said for many primers!
4. Over Metal Imperfections — Not only does epoxy primer have great adhesion and sealing, but a high-build formula helps fill small imperfections in the metal. It can even seal small cracks and dents because of its amazing adhesion properties. When you’ve used body filler on an area, epoxy primer will help even out any small bumps or crevices leftover after sanding.
5. Use It for a Final Sealer — A cool trick we’ve been doing for the past few years is using our epoxy primer as a final sealer before our base coat. Simply reduce it 50% and lay a coat or two down to seal up all your work and have a nice surface to lay your base coat over top of. The primer has excellent adhesion to most topcoats and will help keep actual paint from flaking or peeling. This is great peace of mind for a lasting paint job.
6. Use It To Protect a Long-Term Project — Not all of us have huge, climate-controlled shops our project vehicles can sit in until they’re painted. This means you may have to push the project outside overnight or while you do maintenance on the daily driver. Maybe you have a damp shop that flash-rusts metal as soon as the temps change? I like to use epoxy primer to seal my work at the end of the day. This way, if I can’t get back to it right away, I won’t come back to a surface-rusted mess! Keep a handful of our 2K AeroSpray™ Epoxy Primer Aerosols on hand for sealing up small areas. They will save you time compared to getting out the spray gun, mixing up primer and then having to clean everything back up! Note that if you let a vehicle sit in epoxy primer for five days or more, you will need to give it a light scuff sand before painting.
If any of the above scenarios apply to your project, consider using Eastwood direct-to-metal epoxy primer as a foundation. We offer this automotive primer in many forms, including the new OptiFlow Epoxy Primer Roll-On Paint System. If you’re still not sure which type of primer is right for you, or you are looking for assistance applying this sealant, many other guides and videos are available in the Eastwood Garage and How-To Center. Call or email Eastwood seven days a week for one-on-one advice from an auto painting expert who will help you Do the Job Right.
Can Epoxy be used as a sealer over acid etch? If not, what would be a good sealer?
i removed all of the paint with 80 grit paper some of it is down to bare metal and some down to the primer. what grit paper do i need to go over it with before i use epoxy primer
My 84 Bronco has a totally rusted Hood and Cab top. I have sanded with 80 grit and sanded thru rust to where I have a speckled or salt/pepper look ie (very very shallow low rust spots and partially thru the top of original oem primer). What type of prime should I use ? 2k DTM Expoxy . What or when would a filler primer be needed. The Bronco will not be painted for several months and will sit outside some of the time. To take to bare metal would require sand blasting which is not available in my area.
I’m doing a 87 Regal vinyl top removal project and will paint roof to trunk lid for now but this might be temporary but the car might sit out in the rain. I have some bare metal so do I epoxy it and will that be good enough or just paint that area with B/C but 2 light coats till I can do it right. I don’t want to spend much right now.
We would start with an epoxy primer first and build up from there. Hope that helps.
My covette has a recent 2 stage urethane paint job in good condition. I plan to do a color change and want to know what the best primer is to cover the Urethane and other parts of the. body that are down to fiberglass.
Hi David, Yes we usually suggest to apply a urethane primer and block it flat before applying paint.
Thanks for the info. I’m buying used doors and hood for a trailblazer so I’ll be stripping them to bare metal so using 2k apoxy primer should go first correct? So than do I put a second finish primer down before I paint? Will be painting whole SUV so to match everything.
Hi, If there is bare metal exposed we would suggest using Epoxy Primer to seal it all up.
After bondo what do i seal it with,just primer, or apoxy primer filler? or can I just spray 2k primer? I can only do 1 piece at a time, like the roof, then the doors and then the side bed of the truck, am I going to have a problem doing it that way? Thanks
Hi, Yes you can apply it over top. We’d just suggest scuffing the encapsulator with at least a scuff pad before applying.
can i put epoxy primer over rust encapsulor
Very informative,thank you.Trying to learn the basics.
Thanks for the brief explanation. It’s been 25yrs since I painted cars, and techniques/ materials have changed a bunch!