Posted: Sat Apr 30, 2016 7:21 am Post subject: Sandblasting
I'm planning to have my M38 blasted. It's disassembled and ready to go. I'll start with the frame followed by the tube, fenders, hood, grill, windshield and tailgate. The paint shop is standing by to prime and paint afterwards. The blaster will be using silicone sand. I've read about blasting problems from pitting to warping. Should I be concerned?
Joined: Jun 17, 2012 Posts: 159 Location: Minnesota
Posted: Sat Apr 30, 2016 8:14 am Post subject:
Absolutely you should be concerned. First and foremost, make sure the person doing the actual blasting has LOTS of experience. A powerful blaster in the hands of the inexperienced only spells disaster. They have to be very meticulous, moving the blast nozzle in very specific ways. This is especially critical with large, flat panels, such as the tub, hood and fenders. The guy I use has over 40 years experience and he still has to be very careful and mindful of what he is doing. He also does not use silicone sand, he uses black magic, a kind of recycled material. He says it does not generate as much heat as sand. Warped panels are very hard to correct and could cost a ton of money to fix. If the parts have mostly paint and little rust, I would consider soda blasting for the body parts and sand blasting only for the hard metal parts, such as frame and wheels. Bottom line, ask lots of questions and provide specific expectations, before entrusting your parts to them.
Dan _________________ Dan Schultz
MD20035 9/1952
MC70324 dod 6/52
GPW 14944 dod 4/10/42
K38 Linemans Trailer 4/43
M100 Trailer 01177488 dod 8/51
Absolutely you should be concerned. First and foremost, make sure the person doing the actual blasting has LOTS of experience. A powerful blaster in the hands of the inexperienced only spells disaster. They have to be very meticulous, moving the blast nozzle in very specific ways. This is especially critical with large, flat panels, such as the tub, hood and fenders. The guy I use has over 40 years experience and he still has to be very careful and mindful of what he is doing. He also does not use silicone sand, he uses black magic, a kind of recycled material. He says it does not generate as much heat as sand. Warped panels are very hard to correct and could cost a ton of money to fix. If the parts have mostly paint and little rust, I would consider soda blasting for the body parts and sand blasting only for the hard metal parts, such as frame and wheels. Bottom line, ask lots of questions and provide specific expectations, before entrusting your parts to them.
Dan
The condition of my body panels and tub is good. There is some surface rust where paint doesn't exist. The jeep has been stored in a covered shed for nearly 40 years. I only have two choices when it comes to hiring the blasting out. I suppose I can purchase the media to be used and insist on pressure to be used. He will be charging me by the hour so it'll be to his advantage if I impose application limits that result in more time to do the job. You mentioned black magic which I think is a coal product and available at the local Tractor Supply. What about soda? Seems many recommend it to eliminate pitting and warping. Finally what is the optimum pressure? Thanks
Joined: Jun 17, 2012 Posts: 159 Location: Minnesota
Posted: Sun May 01, 2016 12:53 pm Post subject:
Sounds like soda blasting or chemical remover for you would be best. Rust needs more aggressive tactics. As far as pressure, I don't know, I leave that to the professional. Most sand blaster can also soda blast, may be more money tho. _________________ Dan Schultz
MD20035 9/1952
MC70324 dod 6/52
GPW 14944 dod 4/10/42
K38 Linemans Trailer 4/43
M100 Trailer 01177488 dod 8/51
The old paint has become brittle it spots. I could use a sander and try to prep for primer/paint but I afraid old paint remaining will be an unreliable base. What did you have in mind?
Sounds like soda blasting or chemical remover for you would be best. Rust needs more aggressive tactics. As far as pressure, I don't know, I leave that to the professional. Most sand blaster can also soda blast, may be more money tho.
I'd prefer soda and would gladly purchase the media for hired. Don't want to spend too much $ but then again don't want wrapped or pitted panels either. I'll run it by the blaster and hope he appreciates my concern. I'll let him blast the frame with sand first. I'm less concerned about it relative to sand.
Joined: Feb 17, 2012 Posts: 530 Location: Del City, OK
Posted: Sun May 01, 2016 8:43 pm Post subject:
You can have it sandblasted... the secret is to turn the pressure down to about 100 PSI and have them shoot the panels at 45 degrees not straight on. This keeps the panels from heating up and warping...
I have had my M-38CDN and a Willys Station Wagon blasted this way without problems... Will be doing my M-38A1 tub, fenders and hood this way also...
I learned this from an old gent who used to sandblast cars for folks wanting to build hot rods... he has since passed on... RIP.
But sound advice...
The black magic is actually Coal Slag... I run it in my blast cabinet. Almost no dust other than the material you are taking off. I buy it from a local supplier for about $20 per 80# bag (fine), this will fill the blaster two times.
Hope this helps someone. _________________ Hal, KB1ZQ
TSGT, USAF (Ret)
1952 M-38 CDN CAR 52-31313
1952 M-100 Strick #104
1951 Willys Wagon (For Sale)
1954 Willys M38A1 201001205
Tornado Alley
Del City, OK
Joined: Feb 20, 2007 Posts: 606 Location: Illinois
Posted: Mon May 02, 2016 7:41 am Post subject:
Your professional is going to use silica sand?? Inhaling particles from silica sand "sandblasting" can cause silicosis - a fatal lung disease, and cancer. Absolutely perfect breathing protection is a must. That's why people use Black Beauty or soda or glass beads or walnut shells other media that does not have the health risk. You might want to visit with your "professional" about his choice of media again. _________________ 1951 M38
Joined: Feb 17, 2012 Posts: 530 Location: Del City, OK
Posted: Mon May 02, 2016 7:43 pm Post subject:
My Professional, uses air masks and hoods, they are a commercial business and blast oil field equipment... they have been around for decades... I am quite sure they know what they are doing...
The sand problem is why I switched to Coal slag in my blaster at home... _________________ Hal, KB1ZQ
TSGT, USAF (Ret)
1952 M-38 CDN CAR 52-31313
1952 M-100 Strick #104
1951 Willys Wagon (For Sale)
1954 Willys M38A1 201001205
Tornado Alley
Del City, OK
Contrary to popular belief, sandblasting does not generate enough heat to warp a panel. In fact, the air cools the metal down. what does happen is the metal is peened. This happens when a particle (sand, beads, walnut shells etc.) hits the metal with enough force to compress the metal. it also does some funky things with the metallurgy, hence the reason for shot peened rods/gears. Essentially the sand stretches one side of the metal thus causing the warp. the reason the "pros" don't warp panels is because they don't shoot the media perpendicular to the metal. You can rent a blaster and run it on a lower pressure and shoot at an angle and nothing will happen. You have to really pound on 18 gauge steel to warp it. Also, lighter material will have less impact than heavier stuff. think: what hurts worse, a 100 mph sponge or bowling ball. Materials that hit and shatter would also have less force on the metal. The heat is not the problem. If you take your jeep to someone that thinks the heat is the problem, he is more likely to ruin the metal than you. It takes less time blasting a panel with highly abrasive material at a higher pressure which means he has less time in the product. All it takes is the local blasting kid trying to finish up before lunch and you have a warped jeep. Test the heat theory by blasting a scrap of sheet metal. _________________ Jason M38A1
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