I like to DA sand with 80-180 after blasting removes all the blast residue then I use a wax and grease remover allow to the cleaner to completely evaporate, blasted metal like to soak it up
Okay, I have heard this is NOT what you do. From everything I have read one should use the epoxy primer directly in bare metal. I'm curious about this. Supposedly the epoxy primer goes first (after cleaning prep), any filler over that, and then paint, etc. curious to hear about this. Sent from my iPhone using The H.A.M.B. mobile app
etch is for urethane products and some polys epoxy is for bare metal the reason I mentioned I DA sand first is that I dont like priming over the residue left after the blaster on sheetmetal sand a small area and notice what sands off I usually dont do this with frames mix epoxy, ,make sure you allow it to sit after mixed per instructions called 'induction time' (most epoxies require this) I will usually apply a filler primer the next day (most epoxies have a 72 hour 'open' time this is the time you can apply anything over it without re-sanding I have had issues priming on epoxy too early, especially with polly filler primers
John, what would that matter. I realize there are oils in pecan shells and other things but using a wax/oil remover for all types. I used coal slag when blasting but can you post up answers to the various media used when blasting and cleaning. Sent from my iPhone using The H.A.M.B. mobile app
Because this is a public forum and I want to learn as well, can you provide the different cleaners for given media?? Sent from my iPhone using The H.A.M.B. mobile app
Knowing what media was used could help determine the procedure to follow. The part should be free of wax, grease and other contaminants before any blasting is started. Blasting could, depending on the media, force contamination into the newly formed surface scratches. I'm a firm believer is using wax/grease remover before any work is started on a panel and never again in the process. W/G remover leaves residue unless wiped completely clean with clean rags. It is not meant to be left to evaporate. Wipe some on a panel sometime and leave it to evaporate. A film will remain. For this reason I don't recommend using it, or any liquid for that matter, on blasted surfaces that have been scratched creating tooth because they can't be wiped dry/film free. The drying cloth can't get to the bottom of the scratches. Instead use clean, dry compressed air. Blasted surfaces that have been blasted with non aggressive media leaving no scratch I suppose could leave residue that air alone won't remove. In that case I could see using W/G remover to clean it off but I would prefer using a solvent such as PPG DX 320 Fast Evaporating Solvent. Sand then with 80 or 180 to create tooth for the primer. I would use compressed air only to clean after that. Like the man said, blast, clean, prime. Best to plan well and try to get 2 coats of epoxy sprayed asap after blasting before flash rust sets in. It's worth noting too that surfaces that have been "opened up" with aggressive media will flash rust far faster than those that haven't
I can see the point in cleaning but I'm having a hard time with the sanding to create tooth comments. The as blasted surface is rough to the touch and very toothy IMO.
the primer doesn't need that rough blasted surface to adhere why make the primer do more work that it has to a nice smooth 80-180 surface is perfect also sand that blasted metal and watch what falls off if you look at blasted sheetmetal under a microscope it has an extremely rough surface that is not necessary for primer to adhere roughness does not always = better adhesion sanded is also easier to clean it wont snag the rags when you wipe it off some cleaners will say not recommended for blasted material the rough texture makes it very hard to wipe off the contaminants that may be trapped in the valleys of the roughness it also slows the flash of the cleaner
I have questions about process as well but I don't want to steal the thread. Once the OP has his answers and is satisfied I will chime in with a piggy back question. My A body was roached in a fire and I have been resurrecting it. The surface looks like an orange peel bare metal but pitted. That'll give you an idea of where I'm going with my line of questions but until the OP is good I'll hold off. [emoji6] Sent from my iPhone using The H.A.M.B. mobile app
stole this one from another site "Two things cause fire panels to peel. Smoke and rust in the pores of the metal. Remove both and you will have NO problem with peeling. Iv been in the body buisness for 27 years now, and I will tell you that if the burned metal is sand blasted then immediatly sanded and coated with an epoxy or etch prime, you will not have any peel problems. The peel problems occur when the metal is not properly preped and the pores of the metal were not cleaned out with a blasting abrasive, weather it be sand, aluminum oxide or gl***. Plastic Media will not do the trick because it doesnt clean the metal, just takes paint off."
As said above, sand, blow clean and spray away with epoxy. The reason for sanding is to knock down some of the blasting profile, as we know primer or paint is thinner on edges, if you can imagine the surface after blasting is a bunch of sharp peaks, by flattening those peaks you will have better coverage and a smoother finish. Depending on the media used the profile will be greater or less. I've sprayed hundreds of gallons of epoxy this way in industrial applications and never had an issue. Good luck! Sent from my iPhone using The H.A.M.B. mobile app
Good stuff. Thanks. I won't be able to sand my panels after a second light media blast Bc it would do no good. The small poc marks from fire and then putting rust would mean that ~75% of the metal would even be touched by sanding as it sits lower in the poc craters. I had to blast it first so I could hammer and weld on them. Left them bare except for the cowl section which I sprayed with a cheap primer temporarily. All of it will get another blast prior to epoxy. All good stuff in this thread that I need to know. Thanks for starting it Blue! Sent from my iPhone using The H.A.M.B. mobile app
9'x 15' x 80" sitting on a canvas tarp. 6 mil poly and the walk in door and the end doors will get intake filters. The exhaust will be a filter box hooked to a 12" 2800 cfm confined space vent fan. Going to hang some lights inside too, then it will be ready to use.
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