I’ve been asked to help shot-blast a concrete floor. It will then be covered with an epoxy finish. Is anyone familiar with the shot-blasting process or equipment? Any tips or cautions to share? Thanks.
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I have an aquaintance who does this stuff for a living. It is not an amateur operation.
The equipment he uses is from a company called Blast-track. Can you provide a little more info as to what your situation is? I see in your profile you are in St. Paul, and they do work in Minnesota for a couple different companies. Are you the primary contractor, or a painting sub? They do some prep only jobs for a few painting companies in the area here.
There are different sized blasters, and other equipment to get into corners.
Basically the machines shoot a stream of steel shot at the concrete to roughen the surface. This gives more surface area for the epoxy coating to "bite" into. Most of the shot is recovered back into the machine.
Bowz
It's a garage floor. There is an old section of floor and a new section laid up to it. The idea is to grind down a few imperfections at the seam between old and new and blast the whole thing so it will receive the epoxy.I'm there working on some deck and fence repair and my boss told the HO that, sure, we can do that, too. He's planning to rent the equipment so we can do this ourselves. The machine he's getting is equipped to recover the majority of the shot and apparently runs on 120v. He's gung-ho about it and I'm trying to find out as much as possible before anything can go awry.
Old garage floor would be a red flag to start. oil contamination often will have soaked into the concrete and will not be removed by shot blasting. In time it will cause the epoxy to let go, and start peeling. There are products made to seal this before hand, but my understanding is they are not real cheap, and you would want one compatible with your topcoat.
Another problem can be water vapor penetration coming up from the soil. If the concrete was not laid over a vapor barrier, that can be trouble in some situations too.
i don't know that any of their shot blast equipment runs on 120v, but a lot of their hand grinders and scarifiers do. Their machines are propane powered.
I talked with the aquaintance tonight, and told him that someone may call him with some questions. I'll e-mail his number.
One thing they do while spreading the epoxy is where old golf shoes so if they have to step in it they don't leave a big track.
I asked about what type of job this was because I am wondering if you would still have the proper liability coverage. One of their disasters was getting a few steel shot into the hydraulic lifts in a service garage. Trashed 10 giant cylinders for lifting up cars. Can't see a carpenter's insurance being to keen on paying that bill!
Bowz
I'd rather plant flowers. I never really cared about how pretty my garage floor was. It's a garage, after all.