Sandblasting Windshield

[ColKilgore2860]

I am cleaning up a 1952 M38. The body is amazingly straight, so a DA, and some elbow grease is working well. The windshield looks to be my biggest challenge. So many nooks and crannies! I bought an $70.00 Lematec AS118-2 Portable Sandblaster on Amazon. It is a small hand-unit that has gravity feen from a reservoir on top, or you can attach a hose as well. I never sandblasted before, and I can see that it is slow-going as can be, but effective for little ridges and corners. etc.
I have searched for information on the Google, there is plenty, but I am still confused as to what I should be using for abrasive. I bought two kinds at my local Tractor Supply, one, labled Black Diamond glass 80-mesh, and the other, Black Diamond Coal slag. The glass works, albeit painstakingly slowly. I think it might be too fine, and wish it was more aggressive. I tried the coal-slag, but it must be too coarse because it would not go through the gun. And yes, I used a water filter on my big compressor, keeping the pressure down around90 PSI.
What do you all reccomend for blast material? Another option would be to use aircraft stripper, but I have not used any for 30 years, and the new stuff works about as well as water. Maybe it will be more effective when the weather is warmer, but I have my doubts. I also have a Campbell Hausfeld AT1251 30-Pound Capacity Sandblaster, which I just looked up on Amazon, which looks to be another cheap unit, but maybe the Coal-slag might work in it.

Ideas? Observations? Can you reccomend the perfect abraisive for me?
Thanks!
_________________
Adam Jahiel
Photographer
Story, Wyoming
M38A1 & M38

[wesk]

Normally to insure the least amount of material damage either "Glass Beads" or "Soda" Watch this video https://www.youtube.com/watch?v=S5VgfY3Kgm8
_________________
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

Mjeeps photo album: http://www.willysmjeeps.com/v2/modules.php?set_albumName=Wes-Knettle&op=modload&name=gallery&file=index&include=view_album.php

[wilfreeman]

Hey Adam, I buy my blasting media at a local bulk supply business close to me (about the ONLY thing that I can find close to me!). They sell coal slag, Black Beauty, and glass beads. I can buy an 80# bag of the BB or coal slag for $8 and 50# of glass bead for about $6 in a variety of mesh size. These products are repackaged and sold to the chain stores in their own packaging. So they are likely the same as you can buy at Tractor Supply and Northern Tool stores.

Anyhow, coal slag will be your most aggressive - it works really well on multiple layers of paint or powder coat. But, as you said, it is very coarse and takes a larger nozzle. It is also not screened very well. I found that sifting it through my bead blast cabinet screen got it down to a mesh (I couldn't tell you what mesh that is) that was consistent and worked well in my syphon gun and pressure blaster.

Black Beauty (or Black Diamond) is pretty consistent, but 80 grit is much less aggressive - although safer if you only have a layer or 2 to cut through.

Usually when blasting, I will blast on top of a tarp. After I run through a bag of media I will pull the tarp up and scoop the media up into a 5 gal bucket to be screened to get the paint chips and other crap out of it. Then I re use it in the blaster. I can usually get 2-3 uses out of it before it degrades too much or disappears off of the tarp.

Glass beads are the least aggressive of course, but leaves a very smooth finish. Often this finish will need to be scuffed up before applying a DTM (direct to metal) primer or etching primer. Glass beads also degrade quickly depending on air pressure.

In your case, as long as there isn't a BUNCH or paint built up, I would stick with the Black Diamond with as large of a nozzle as your compressor will allow. You can buy the nozzle packs with different sizes for the Campbell Hausfeld gravity blaster at Northern Tool and I am sure they are on Amazon and eBay too (cheaper).

Blasting requires a LOT of air with the larger nozzle sizes running 90psi. I use a 5hp 24cfm compressor with an 80gal tank through a 3/8" hose. Although a larger one would be nice and speed things up a little, I usually don't have to wait on it to build pressure - it just runs CONSTANTLY while blasting. I have run the gravity blasters using a 2.5hp, 5cfm, 20gal tank compressor with a small nozzle and a 5hp, 14.5cfm with 60gal tank with medium nozzle. They both worked, but it was slower going having to wait on tank pressure to build back up. You can also daisy chain tanks to help with air volume. This will give you longer blasting time, but sooner or later you will have to wait on the compressor.
_________________
Matt
1953 M38a1
1964 USMC M38a1
'51 USMC M100 trailer, '54 M100 trailer, '90 M101a1 trailer
Http://wilfreeman.wordpress.com (M38a1 build blog)
http://m38a1usmc.wordpress.com (USMC M38a1 rebuild blog)

[OKCM38CDN]

You can get coal slag in a medium grit and that works great for me...
_________________
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

[dpcd67]

I use black coal slag; fine or medium. Using soda or glass beads won't work if you really want to remove rust or thick paint; those are for delicate parts.
However, the most important thing is your compressor; is it big enough to keep up. The metal surface will be rough but primer will smooth it right out.
If you had a commercial blaster you have to be careful with warping but the little hobby ones are too weak; and are frustrating. At least get one of the sealed tank type.
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M38 23100 June 51
M38 34523 Sep 51
M606/CJ3B 1964 Kaiser 57348 118458
M37B1 1963
Willys MB 1944
Ford GPW 1942
Dodge WC63 1943
Dodge Power Wagon WM300 1967
Plymouth Barracuda, 1973, 340 4 barrel
All ground up restored by me.
Lots of others.