primer

[WernerVC]

I am in the process of removing all the old paint to bare metal. In order to prevent rust, what kind of primer should I use or is etching also a good solution. What is the difference and are there limits as to what kind of paint can be applied later. Can the primer be applied with a brush because I am just doing one panel at a time so spraying the primer would waste a lot on a small panel or surface. I removed the old paint with a 4.5" fiberglass  alu oxide covered wheel. Works great. Will try soda blastingin the nooks and crannies. Anybody has experience with soda blasting ?

[crashbash]

self etching primer 1st, then build up primer coats.....you can buy self etching primer in spray cans from automotive paint store, quarts, gallons,  etc  green looking stuff you might have seen on new aircraft assembly line pics

[rficalora]

What about using an epoxy primer as the 1st layer.  Any material benefit?

[MG four six eight]

I use Dupont Vari-prime and then cover it with PPG K-36 epoxy primer/surfacer. Vari-prime is a self-etching 2 part primer that is yellow/green in color. It is thin for spraying but I have brushed it on before, for small areas.

Bill

[mgbreis]

I've painted three cars now, always using epoxy on first coat over bare metal. I've never used etching primer and while I've had issues, I've NEVER had an adhesion problem. I don't use etching because it has to go over completely bare metal and after I've stripped my cars I can't say there aren't any nooks and crannies that still have a little paint here and there. If you don't want to spray, I guess you could try rolling on the epoxy primer, but I can't say exactly what the paint would do to a foam roller. You're just promoting adhesion, sealing the metal and preventing corrosion. You will want to sand out all the flaws when you're doing the 2k and block sanding steps.

[flitner]

I too advise to go with epoxy primer over bare metal, I used Variprime as well as Duponts lower grade etching primer, body filler does not adhere to etch primer even after a year of being applied, epoxy can be filled over.

[rficalora]

That's what I thought.  I put epoxy primer on after stripping to bare metal but I'm no expert so didn't want to say it was better till others chimed in.

[nobogez07]

Etch primer is for use on aluminum not steel!  For a steel body it's advisable to remove all prior paint followed by a complete cleaning (Trisodium Phosphate is a great choice) and finally if you can find it, a hand wipe with an iron phosphate product.  This provides a conversion coating barrier much like OEM auto companies do prior to e-coating all bodies. This conversion coating acts as a sacrificial barrier to any oxygen that will eventually permeate through the paint film over time.

This process is why you don't see cars today that have the "cancer" you saw in cars years ago

[Preform Resources]

Thanks Doug, very informative ! which phosphate product  do you suggest ?
Dave

[BlownMGB-V8]

You can buy straight phosphoric acid at the hardware store.

Jim

[tdecell]

Soda blasting works well, just not good enough for large areas. Would probably do good for nooks and crannies like you mentioned. It's just a little slow and makes a HUGE mess. And kills grass like nobodys business... unless you hose down the area really good afterward.

[nobogez07]

Where to get a hand wipe iron phosphate?  That's a great question and one I'd never thought of for the average guy painting his or her project car.

We do millions of parts for OEM manufacturers and buy ours from specialty chemical manufacturers.  Using straight phosphoric acid is not reccomended as there are no inhibitors added to control the reaction.  So the anwser to the queston would be as follows:

1. If you know of a company that paints its own product in your area, you could go in and ask them to buy a quart or so or their Iron Phosphate (it'll be diluted 10:1).  The cost to you would resonably be $10.00.

2. If you can't find any, as a last resort I'd go ahead and send a quart to you for $10.00 plus shipping and handling.(Please understand we're not a retail company so this is not our business!!)