I needed to get some epoxy primer for sealing internal parts like the insides of suspension consoles, tunnels, etc. Eventually, I'll be spraying the car with PPG Deltron so the local paint supplier steered me to DP50LF (gray) primer and I picked up a gallon. But this stuff is really expensive (>$300 for paint and activator) so I'm wondering if there is a cheaper option that will provide as good of corrosion protection for internal parts that won't get a top coat other than cavity wax. But I don't want to sacrifice protection, so am happy to use this stuff if it is the best for this purpose. I used Eastwood's rattle can epoxy primer inside my passenger long and it worked well. But once activated, you only have 72 hours to use the whole can. I need something that can be mixed in small amounts for when I only need a little paint.

Also, I bought gray primer because I'll be spraying silver metallic. But I'll be spraying surfacer over the primer. Is there an advantage to exchanging this paint for DP40LF (gray green) to provide a little contrast for when I spray surfacer?

Finally, how much primer should I expect to use for 2 coats on a full bare metal rotisserie job inside and out?

SPI two part ................
https://www.southernpolyurethanes.com/

Can be sprayed over OSPHO with the manufacturers blessing.

Cary -
I see they specify:

Precautions:
NEVER use SPI Epoxy over a Soda Blasted vehicle unless you call us first for
proper neutralizing instructions.

Just curious if you've soda blasted and neutralized and if so, what did you do, is it worth the extra effort, etc?

I'm thinking about soda blasting vs other media so any info appreciated.
Thanks!

Chris to me it would depend on the budget.

I have a friend here in town that restores and builds sunbeam tigers. He will mix up a batch of epoxy and spray the car, and what he has extra he will poor into all the holes on the chassis, and then stand their and spin the car on the rotisserie until the epoxy stops flowing out.

If I had deep pockets, I would dip, and then have the car EDM'd

Soda is not bad but ti is a base, you will get a reaction with it, and the epoxy, so what SPI is trying to tell us, is they don't want you to do this with out knowing exactly what is going on chemically. And they have so much faith in their paint products forming a bonded layer between the paint layers that if you don't follow proper procedures you could have the entire paint section delaminate due to lack of bonding between the metal and epoxy layer.

People love to take short cuts then blame the manufacture for their stupidity. If you soda blasted and then went to epoxy, to many different things could go wrong.

So I wonder what their instructions are? Murick acid wash, water wash.

For the Ospho and SPI here you go from the company it's self.

"The ONLY acid cleaners SPI recommends is Opsho, PPG and DuPont metal preps as long as their instructions are followed to a tee.
Use any other system you want, just do us a favor and use no SPI over them.

There can be NO shortcuts for good results.


Ospho, is a great product for automotive if used right, we give scare warnings because we want people to call so we can make sure they know how to neutralize it, so no problems will arise.
Only one way to use and here it is:

Use as needed and apply as many times as needed to get the spot clean, let dry and leave for months if you want, don’t matter.
To neutralize the Ospho MUST be wet, so if dry, re-wet with itself and let set one or two minutes and with a clean rag and water, wipe off like washing the car and then dry.
Next, then da car with 80 grit, clean with 700-1 wax and grease remover, let set an hour and coat with an epoxy."

I've found DP40lF to do the best
Job. Use to use Variprime(DuPont)
Years ago, it is cheaper but does not
Not work as well as DP40.
Two quarts will do a 914. It mixes
2/1. One coat on bare metal, wait
Thirty min. And spray your high build
Primer on top of it. Do not leave.
DP40 with out topping with epoxy
Primer surfaced.
That's two quarts on a complete
Color change.
Hope this helps,
Bruce

Man, great info. Thanks all! Of course I have more questions now.

1. Cary, are you shooting the whole car with SPI or just the hidden parts? At half the price of PPG, it is attractive. But I thought I needed to stay in the same paint family for anything that would be topcoated.

2. is there any difference between Ospho and Jasco? The both seem to be phosphoric acid with zinc additive (I think). I've been using Jasco only because it is what the locl Lowes carries. The directions seem the same. Should I be using actual Ospho instead, or am I good with Jasco? BTW, the DPLF data sheet says "Chemical treatment or the use of a conversion coating will enhance the adhesion and performance properties of the finished system.". I assume that would include Ospho or Jasco.

3. Recoating primer. The data sheet says it can be recoated up to a week later without cleaning, sanding, and recleaning. My plan was to shoot a coat of epoxy; then go over all of my butt welds and any stray grinding nicks with a thin layer of FG filler; then a second coat of epoxy followed by surfacer; then block etc. before basecoat. Is that second coat of epoxy not necessary? I'm happy to skip it and save time and material.

4. If it only takes a couple quarts to shoot the whole car, then I will have plenty of extra with what I already have. Maybe I should just stick with the DP40LF for everything? I don't think the internals will require much. Maybe a half quart.

Thanks again everyone for the great advice. I'm loving the rotisserie spin extra primer disposal method. The last time I painted a car was with lacquer using a high pressure siphon gun. That was a long time ago.

DP epoxy primer is for rust resistance so putting it over filler won't help.

When I did extensive rust repairs to my 914 in the early 90's , I painted the passenger compartment floor gray DP / sills and shifter tunnel black DP since I run sans carpet.

What I've found about e-coating is there's a thing called "Faraday cage" effect that makes it hard for the coating (and plating) to get into box sections and deep U shapes.

Sorry I'm late to the party. PPG epoxy primer is absolute one of the best products to use. I started my career in Body as a restoration tech. We used this on all bare metal. I currently work in the industry and would not recommend going the cheap route. If what you use on the steel doesn't stick or prevent rust you will regret it. To do paint correctly for a long life finish you will be better off going with quality products.
I still do paint work at home. Recently painted some stainless steel parts and sprayed epoxy primer and top coated with base & clear. Stuff absolutely takes a beating.
Just my two cents.
Bill