2020-B1-10

Author Topic: Advice on sandblasting  (Read 1663 times)

roadking77

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Re: Advice on sandblasting
« Reply #40 on: July 30, 2019, 07:03:42 AM »
I am no where near a pro painter but agree with what Form said. I know what I have done and it has worked great so far. I know things may be a bit skewed you being down under and all, but I bought a gallon of epoxy primer. I used it on my 77 and on my 79 I am now restoring. I would put that directly on the bare metal. Something else I do before any paint is to clean the surface with a prep agent. I use a product made just for that. I put it in a spray bottle and use a clean white rag to wipe it off. I will do this process over and over until the rag stays pretty clean.  I use a cheap hvlp spray gun that I get at Home Depot or Lowes. I think they cost around $60 now (compared to the $400 gun I use to paint). The epoxy should hold up for awhile. I did my body work on top of the epoxy then used a 2k primer on top of that. POR is ok I think, but I thought for best results it is used directly on top of rust. Personally, if I here someone say they used POR I think they either did it wrong or did not get rid of the rust, either way to me its bad. I have used a similar product -chassis saver- on my heavy equipment and it works there ok.
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Grand73Am

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Re: Advice on sandblasting
« Reply #41 on: July 30, 2019, 07:38:28 AM »
I agree with FormTA. A gallon of epoxy primer, plus the hardener of course. You could spray it with a primer gun that has a tip of 1.8 for a thicker coat in one shooting. And the primer gun would be useful later on for when you spray some of the thicker primer/surfacer(sanding primer) over the body for block sanding.

Do not use a schutz gun for the epoxy primer. A schutz gun is for spraying thick undercoating, and not suitable for spraying paint. It would be like using a water hose with paint. As FormTA said, you'll be able to spray paint inside any panel that you were able to reach with the sandblaster, so a spray gun is all you need.

There's no need for POR-15 over sandblasted clean metal. Only time it could be useful is if you cut out a rusty piece of panel and you find some surface rust behind it. If you didn't want to make a mess sandblasting again, you could wirebrush as much of the surface rust off as you can and brush on a coat of POR-15, which would stop the rust. After it dries, you can proceed with your metal patching, knowing that the metal behind it is protected. So, it would be good to have a quart on hand. It's only for painting over hidden rusty spots like that, so don't use it for anything else. It's not for your exterior priming, bodywork or paint.

As for how much time after sandblasting do you have before priming. I agree with priming as soon as you can. But cleaning the car out thoroughly after blasting could take a long time on its own, so you might need more time. I think you can wait a couple days before priming, if you can keep the car dry. But to reduce the time that the car sits in bare metal, you could do a quick clean out of the inside of the car, and then thoroughly blow off the outside of the car. That wouldn't take long. Then you could spray epoxy primer over the outside of the car right away, to get protection on the exterior sheet metal, which is most important. After it dries a day or two, you can go back inside the car and take the necessary time blowing and vacuuming up the sand that's left in there. Once you're satisfied with your interior cleanup, you can spray your epoxy primer inside.

Once you have the car in epoxy, you can take your time doing your bodywork, since the epoxy will protect the metal indefinitely.
Steve F.

FormTA

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Re: Advice on sandblasting
« Reply #42 on: July 30, 2019, 08:49:00 AM »
Everyone is spot on. I only had a few minutes this morning to respond so it was kind of short and to the point. 

Do your blasting, then clean out the inside the best you can and then use a paint prep/wax and grease remover to clean the outside just before paint. Once I wipe bare metal with a cleaner it will show surface rust overnight (little humid here). The 1.8 tip is a good idea though I have never sprayed epoxy through that size, only 2k primers but even if it leaves an orange peel  finish it wouldn't matter.  Most epoxy needs to be scuffed after 3 days if you need to apply another coat or 2k primer. On flexible items I thin epoxy and spray it as a sealer before top coats.
79 Trans am low buck LS swapped
79 Formula 301 (Work in progress)
67 RS Camaro (This one is next)


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Re: Advice on sandblasting
« Reply #42 on: July 30, 2019, 08:49:00 AM »
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