Acid Etch Primer


Promoted Users
Hey guys
Going to be trying my first paint job based using SPI epoxy primer 1:1. I think I was told not to scuff and apply onto and acid etched primer.
I dont really know what sort of paint is on my truck right now ....... looks and feels like a primer as its very coarse/matt - and doesnt feel "thick" to metal if that makes sense - but really no idea ..... but I also dont want to take down to bare metal - working in carport and my wife will kill me with teh mess im going to create anyway.

Someone at SPI mentioned doing something like rubbing paint thinner or somethng on it 10 times and posting pics of what came off ....... but I foget the specific details.

Anyone got a way for me to tell - also what is the issue with epoxy primer going over scuffed old acid etched primer (if it is)?




Promoted Users
Epoxy will have poor adhesion if applied over an acid film.

Would that still be an issue on primer thats been on a trucj over 5 years ? Would have thought any acid would be neutralized pretty quick. But shows what I know.


Promoted Users
That a question for Barry but it’s my understanding the acid film remains. Maybe call him on the tech line.


Jim C

acid etch primer will wipe off with a rag and lacquer thinner, reducer or acetone. squirt some on a rag and wipe the surface a bit. if it melts right into the finish that is on the truck then you have issues.


Promoted Users
ok. I'll do that somewhere and post a pic for you guys .........
If it is acid etched primer - how long would it take to sand back a panel truck ........ I'd have no idea. Use 80 grit ?

My original plan was too

  • Scuff everything with 240 grit and do any small repair I need with body filler (dont think there is much but in some corners of inside door etc). Clean (W&G remover) and tack

  • Epoxy it (SPI).
    Stir with stick - Mix 1:1 with activator for 1 minute and reduce 25% with urethene reducer (due to using a turbine sprayer). Wait 30 mins before spraying.
    Spray 2-3 coats allowing 30 mins inbetween coats.
    Wait 24 hours before SS paint (320 block sanding)

  • Block it with 320 and scuff with red pads in non blockable areas (headlights/jambs)
  • Clean and tack
  • Paint with SS black. (non SPI) - Speedokote Hot Rod Black Paint, Black Satin 2K Urethane (beginner job - cheaper for 1st time out gate)

  • Cut and polish as desired

I assume if its an acid etch primer ......... follow the same process but as a prestep.......
  • sand everything down with 80 git to bare metal or filler
  • wipe down with oshpo if any rust areas needing treatment (allow dry)
  • wipe down with oshpo panel by panel for 5 mins sit time and immediately remove clean towel and water. Dry with another clean towel.

Sound ok ?


Promoted Users
@Barry @Jim C
Heres the video.

Let me know if thats enough to determine - or if need better. Appreciate the assist. Trucks been sitting for 5 years in carport :) I did wipe down first.


Trying to be the best me, I can be
Using acetone like that is almost pointless. Notice how quick it is evaporating in your vid? Almost instantly. If you are going to us it pour it directly on the panel let it sit for 30 seconds then wipe. Looking at your video I'd say it's not etch primer though. More likely 2K urethane of some sort. In your first pic you can see where the primer has texture. Etch will not have texture.
So what are your expectations with the vehicle? Painting over unknown primer is a real gamble. Looking at that first pic I'll be willing to bet there is a lot of body filler in the truck as well. And using epoxy over unknown previous primer/work really defeats the purpose of using epoxy to begin with. Epoxy is your foundation. Putting it over an unknown foundation won't make the unknown foundation any stronger, better, or last longer. Only telling you this because of the expense of materials and the amount of labor involved. I imagine you would be disappointed if within a few months your job that you worked so hard on starts having issues. If all you want is some paint on it that's fine but if your expectations are more for your project you are so much better off stripping it.

Oh and FYI if you paint it with a matte/hot rod black there is no cut and buff. That only applies to regular gloss finishes. Any cutting and buffing would destroy the matte finish. If you are planning on a matte finish look at SPI Matte black. It's awesome stuff and priced competitively. I would choose it 10x out of 10 over the products you named. It also sprays very nice, easier than those products especially for a beginner.


Promoted Users
If all you want is some paint on it that's fine but if your expectations are more for your project you are so much better off stripping it.

Appreciate the info - Im washing as much of the dirt I can off it rigfht now ...... to take it for a test drive. Shes only been around the block 1 time before I got her registered - 3 months ago.

Im really looking to do as cheap as possible. But I believe in good products. So its a mix.

1) Painting outside
2) 1st time ever
3) Using a Turbine HVLP not a true spray gun
4) Still lots to do on the truck.

So basically - I want to start using my truck. I am happy to slap something on there knowing (1-4) is the problem not the paint. I priced out using all SPI (epoxy => clear coat) and it was close to $2k. Not worth doing that until I learn a bit more and have better environment to paint in (rent a booth etc).

So this came out closer to $450

2 useable gallons of SPI Epoxy Primer $210
2.5 useable gallons of SS Speedkoate. $230

Hope that makes sense.

If I take it back further I might need more epoxy - unsure how to know how much overspray with the HVLP will save paint etc as never done on such a large area.

Open to ideas - but thats where I am at. This is DD not a show car.

Jim C

thats not an acid etch primer. if i was you and wanted to do that as cheap as possible i would use what you have as the foundation. sand it down with 320-400 grit then shoot the whole truck in a solid color single stage and your done. only thing is that your using a turbine hvlp gun. i have never used one but generally they make alot of heat and should not be used with automotive paint. the solvent systems in auto paints arent set up for that.


Promoted Users
@Jim C
Dammit :) Already bought the SPI expoxy.

I *think* given what most 57 trucks look like - Im probably in a normal position where the base sheet metal is pretty clean and not too many layers of paint ..... but lots of bondo/filler in problem areas. I Think this also due to following pics ......

Chipped Paint - thin - no layers

Same - just rusted (exposed longer)

#3 Typical Problem area in inside front door

#4 Typical problem area near drip seal/edge

#5 Door bondo

I think I will cut it back further than I originally planned ......... so Im happy that everything is smoothed out a bit better ........ and I see one or two areas I'd like to "skim" with body filler.

So I guess the question now is ........... if I take the majority of the truck back to metal .....

1) What do you do if its sitting outside and you you go to paint 12 hours later and its flash rusted.
2) IF the existing body filler sands down find and no cracks or chips - ok ??? Or replace somehow.

Then are steps listed above ok.


Promoted Users
ok never heard back :)

But Im moving on anyway - and have a seperate quesiton .......

If I sand back the truck ...... say saturday with idea of spraying primer sunday
Then late saturday I realize there's a bit more body work to do than planned
And I dont get around to painting till monday

Being in FL I will have a bit of flash rust on the truck come monday morning .....
whats the approach for that


Promoted Users
Is that the preferred approach ?
Or should I give it 1 spray with Epoxy primer to seal it ....... and then do body filler ....... and then 1-2 more coats of epoxy on top.


Taken from the TDS, here is a link to the full sheet, Epoxy Tech Sheet


If you can't get all the bare metal handled in one day then work in sections to get the bare metal covered and then spray your finish coat at once after your done with body work.


Promoted Users
Thanks. That second part on body filler makes it clear.

Im only planning to do a few areas of body filler to smooth out a few imperfections. So think I'll plan to sand back to metal ..... and then immediately lay down 1-2 coats. Then apply skim coats in those areas to level out a bit more and block down .......... then maybe 1 final epoxy followed by SS paint.

I asked my wife about the areas - and she said she wouldnt even bother ..... but now that I know they are there ..... I think I'll tackle them.
Just dont know what else I will find in certain areas as I sand.

thanks for the details

Does anyone have any input on using Glass Cleaner/Windex as a W&G remover. I was reading this threads ....