I have sand blasted a bunch of steel sheet metal parts and 4 steel wheels to remove rust..Surface is on the rough side so what should I do prior to priming?
As long as you didn't use gravel when blasting, clean the dust off and primer it. The as-blasted surface gives great 'tooth' for the paint to stick to.
Self etching primer. https://www.jalopyjournal.com/forum...gh-build-work-instead-of-epoxy-primer.803101/
Everything I have ever sand blasted I have primed with self etching primer, then sprayed on the primer surfacer. I have never had the surface be too rough.
I went out and did a surface roughness check..A little smoother than #400 grit sand paper [wet/dry]....
I wipe the metal down with a surface prep to remove any dust or residue from the sand and oil from finger prints,then use a etching primer. HRP
blow off the dust, wipe with grease and wax remover. Prime with epoxy, let it flash and lay on a wet coat of 2K primer/surfacer.
You don't need self etching primer.......you just etched the surface by blasting it. Epoxy prime and go.
I know I am NEW to the forums.. But I will have to agree here give it a quick "EDGE" for the primers to stick to, ALL bare metal HAS to be prepped... Self etching primers are GREAT for a barrier coat they are NOT designed for "HIGH" build, Do your body work and use a good 2 part filler primer on top. Some shops use Epoxy primers on bare steel others use self etching either way is good, your choice.. A respirator is a MUST ! while using either primer. And STAY away from rattle can primers. (unless it is a small part) The key to a good paint job is always 90% prep pay attention to the edges
When I bead blast, I always wipe it down with the acid "rust remover" from the paint section of Home depot. This will get in any remaining minor rust and converts it to something. Also leaves a coating that will protect it for a few days. Can wipe it off after a few minutes, wash with lacquer thinner, then the oil/grease remover then prime. If left to dry, hit it with 220 /320, clean then epoxy prime. Just need to remove/neutralize if wet, or dry in place.
I've had real good results with Duplicolor self-etching primer, not cheap though. https://duplicolor.com/product/self-etching-primer
Either way I suppose, I got mine at NAPA some time back. These guys have it. https://shop.advanceautoparts.com/p/duplicolor-self-etching-primer-12-oz-aerosol-dap1690/7140110-P
On small parts out of the glass bead cabinet, I wipe 'em down with solvent and then light 'em up with the propane torch. They kinda burn off a foggy perspiration coat and leave behind a nice clean, not surface that takes semi gloss black krylon well. Particularly useful especially during winter. Make sure the torch is off before spray painting.
What I meant was the blasted metal felt as rough as #400 paper does by running finger over surface of each; Not the roughness left by sanding metal with #400 grit..
Thanks for help guys..I have gotten some Urethane 2 part primer #360 by Exel Autobody Products.. Can be used as High build or normal build surfacer [add reducer]..Technicaly should have self etching primer coat first but will work with out or so I am told...Will see how it goes.
Imagine spending months performing rust repair and body work, then endless hours priming, filling and hand sanding each panel to perfection. Imagine the joys of laying down that first coat of paint, basking in the glow of the glass-like sheen, then, once the paint has cured, taking your now gorgeous vehicle to the car wash for it's first bath. Now imagine as you very gently wash the vehicle for no apparent reason a huge chunk of paint suddenly rips itself loose from the door, the anger rising like bile in your throat as the paint continues to come off not in little bits or pieces but in long ribbons, your expensive and time consuming paint job now decorating the walls and even the ceiling of the wash bay. When it comes to paint, primers and fillers the only person you should be seeking information from is the product representative.
Years ago a friend of mine had a car body soda blasted, he said the paint came off on every panel, he said never again. I think this would have been a candidate for self etching primer.
According to the tech sheet, that primer is not for direct to metal. For best adhesion, use etch or epoxy first. Doen't take much, just a binder coat.
The paint falling off after soda blasting is a direct result of poor prep work, it leaves a residue that must be cleaned off Sent from my iPhone using H.A.M.B.