Plastic Media Blasting vs Sandblasting

[clipquito]

Does anyone know anything about plastic media blasting? Supposed to be less harsh than sand blasting. Would you recommend it? I would not try to do this myself. Will farm it out. Thanks. BA

[pistoncan]

I have tried walnut hulls and various grades of sand in my small personal sand blaster as well as a black slag product that is really sharp and good on cast iron but way to harsh for tubing. I can say with some confidence that its hard enough to get the crud off with very fine sand. If you are going to farm it out, I would be concerned with the pressure and the coarseness of the sand the commercial sand blasters use to do horse trailers and tractors. For them its time is money and they are fast. I don't know if there are commercial blasters out there that use plastic media. I have even heard of people using baking soda as a medium.
My compressor has a hard time keeping up with the sandblaster so my pressures are not all that great anyway. (60-125 psi) But you can also regulate how hard you are on the tubes by the distance away from the tubing, how fast you move and the angle you hold the nozzle in relation to the tubes. This might not answer your questons but maybe Steve Pierce will chime in on it. He just blasted a couple fuselages lately. Gary

[clipquito]

Thanks Gary. I was able to find a guy in Helena MT who does the media blasting. He says sand is an 8 on a scale of 1 to 10 for harshness; plastic acrylic is a 3. Sounds good, but was wondering if it is harsh enough to get the junk/paint off. I went to sandblasting "school" with a friend of mine doing a rebuild. He has always used Silicone (?) sand, very fine with a has-to-catch-up compressor. He just yesterday switched to black slag because he said the other is a real health hazard. I wasn't there so I don't know how the slag did. I didn't mind the work/process so much as I did the time. Did 4 tubes in 2 hours. YIKES! The guy in Helena says he will charge $300 for the frame and $50 or so for the tail feathers. The price is definitely right. Seems to know what he is talking about and has a reference. BA

[Steve Pierce]

Sounds like a good deal to me. We use the black slag. My only concern would be is does the plastic media leave enough of a rough surface area for the primer to stick to. If so I would keep him busy for a while. :lol: I am waiting for the temps to come down a little before I start up again.

[Vagabondblues]

You may want to look at Electronics Inc. web site (http://www.shotpeener.com) They have a lot of information about blasting medias, including plastic in their libray. I believe that they also have a approved process for plastic, but it is used on aircraft aluminum skin.

[Jim]

Hi,

clipquito wrote;
.......He has always used Silicone (?) sand,

He was probably talking about silica sand. It's a sand that's real course, broken edged, and will easily make your tubing feel a little like sandpaper. It's dust is also a carcinogen.

I went over by Lake Michigan with a shovel and a whole bunch of buckets and grabbed close to 50 gallons of beach sand from one of the parking lots. Beach sand has been eroded smooth over the years and does a little less "damage" as some would say. The sand was dry enough right from the lot so it easily sifted through an old window screen. Couldn't beat the price.

There's a good chance beach sands are also silica as bricks and some blocks come with the same carcinogen from dust warnings.

[Jason Gerard]

Plastic media is most often used on softer metals. It will not remove rust from steel.

I have used it to clean engine cases, pistons, cylinder heads, valves, etc. in an HVLP type spray cabinet. It's just soft enough to clean with out damaging delicate areas like bearing surfaces.

Jason

[clipquito]

Thanks everyone for the input. I talked to a guy who had a PA12 frame media blasted by the guy I found in Helena. He was very pleased with the work and the process. He too says that it will not take off rust, but says he had no problems getting the prime to stick. He advises an etching primer as a first coat, then the epoxy primer. He also advises painting over the primer. I've heard mixed reviews on this. The PA12 guy says that the primer is porous and won't stop moister. He recommends an enamal paint over the primer. Any thoughts/experience with this? Thanks. BA

[Steve Pierce]

If it won't remove the rust why use it? We have found rust under what appeared to be perfectly good paint. My only reason for blasting is to get the rust off and get to white metal so that I can have a completely clean base for a good two part epoxy primer and then a catalyzed polyurethane top coat. I have had frames that were blasted and primed start to bleed rust from under the primer over a few years just sitting in my hanger and I am in a fairly dry climate.

[clipquito]

Thanks Steve. Good point. Depending on how much rust there is -- of course -- could the frame be media blasted (with the plastic) then wire brushed to remove the rust, or is this too superficial of a treatment for rust? Thanks. BA