Media blast paint prep

[jvb6648]

I'm going to blast my sub frame with black beauty, any need to prep the metal before paint? I plan to use a etching primer. Also any thoughts about using a bed liner producct on the under side of the body. It'll be a driver not a numbers matcher any more.

[69Z28-RS]

I like to treat bare stripped metal with 'Dupont metalprep' or a similar product, and then rinse, dry, and prime.

[m22mike]

I like to treat bare stripped metal with 'Dupont metalprep' or a similar product, and then rinse, dry, and prime.

Cheap insurance, I always  like etching everything before paint. Forget the self etching primer if you etch with a phosforic acid,  and use a good quality epoxy like PPG DP90LF.
 You can buy a gallon of Clean Stripe brand "Prep and Etch" at the Home depot for about 15 bux.

http://www.homedepot.com/buy/klean-strip-1-gal-phosphoric-prep-and-etch-gkpa30220.html

Mike

[69Z28-RS]

that Klean Strip product seems to be in a 'ready to use' form..    is that correct Mike?   The products I've used, Dupont MetalPrep or Jassco, are in a more concentrate form, even though more expensive to purchase, which allows some flexibility in dilution and use.

[Sauron327]

   Just go straight to epoxy on sandblasted metal. No need for an acid metal prep. Unless it's DPLF which has optional additional measures on the TDS. In fact, some manufacturers do not recommend acid prior to their epoxies. Nor are some epoxies to be shot over etch primer at all. If they are, only certain ones within their product line are to be used. DPLF has strict products that can and can't be used with it. Some have explicit sandblasted metal painting procedures on the TDS. I don't pamper my car purchased 29 years ago. No bedliner undercoat and no failure on original floors that were epoxied and topcoated with DDL. Epoxy was the old DP, the good stuff before DPLF forced it out. Now I blow urethane over epoxy instead of DDL. I prefer R-M epoxy now.

   Etch and epoxy are not the same but often confused; two different products with different procedures. Read the TDS for your product, they're all on line. When in doubt ask a rep or the company. A counterperson is not the same as a rep. Many counter employees don't have extensive product procedure knowledge.

[jvb6648]

Thanks for the input. I have to admit that I haven't got the slightest idea what all those initials mean, DPLF, TDS, DDL, R-M, DP. What about the black primer on new sheet metal, remove it or scuff it up and prime over it? Thanks again.

[Sauron327]

DP and DPLF is epoxy, PPG and R-M are paint companies. DDL is lacquer. TDS is technical data sheet.  The black primer of which you speak is EDP coating. On restos it gets removed. However, it gets only scuffed and sealed prior to paint in collision work. I'd suggest going to Refinish Network for more info if needed. It's mainly for shop owners and techs, but they welcome hobbiests as well. Professional resto and collision advice can be obtained there. The regulars try to correct any bad info that's submitted by the less experienced, or by those who are hacks.

[jvb6648]

That's great, I'll do that. Thanks