Repairing Sandblast Damage

[68c10airstream]

I water sandblasted a 1968 oem tailgate last fall and did every square inch of it and took a straight edge to it and didn't see or feel any warpage. I used sand that the lumber store stocks. I have put my hand on the backside of a panel i did years ago dry sandblasting and i got burned instantly. Through the years i have done black paint jobs so my hands are my eyes when block sanding flat panels (black shows everything). I wet sandblasted my snowblower auger housing and there was paper thin areas at the edge and i used blackjack (very aggressive ) and no warpage, so in my world i'm convinced. Good luck.

[MP&C]

Not disputing your results or the method. But comparatively, a water jet uses a concentrated stream of water mixed with an abrasive, and it cuts right through a panel. Did the water not cool it enough?


What I'm saying is that excessive applied pressure and excessive size of media combined are what cause the peening action, resulting in the stretch. Yes, given enough of this it will eventually cause the temperature of the panel to increase. But the temperature does not cause the stretch, it is a side effect of the peening action. Stretch has long occurred before the temperature rises. So any claim that it can't stretch because water keeps it cools is a bit misleading as to the actual cause of the stretch in typical media blasting....call it crafty wording or advertising hype, but sheet metal panels are media blasted every day without damage by observing air pressure and media size, without the use of water. Perhaps the water helps to "soften the blow" so to speak, by having the media in the mix. But as shown in the water jet example, which obviously uses a different delivery method than what you are using, water is not the secret Elixir of Unicorn blood.. Any process used incorrectly may cause damage. Accurately identifying the cause is the secret to corrective action in that method.

[Possmguts]

I am about to have a guy glass/water blast my under cab and bed sides... so what Im reading here... just because he using water to keep things cool does not mean I wont get damage? From what I understand its a fine glass he uses. I was originally going to have him dry ice blast it but he said it wont take the undercoating off Im trying to get off....

[68c10airstream]

I was initially lured in from a guy purchased a pallet of sand. I asked him what he used that much sand for? He said some of his buddies are contractors and pull enclosed trailers and the road salt destroys the paint job in no time. I remarked that if he sand blasts and hits the aluminum body near the frame it would be an ocean of waves from distortion!! His remark was "not at all". I asked what he was using? He said an attachment for a pressure washer! I went to youtube and searched it out, saw videos on it, google searched a vendor and matched my 3800 psi 3.5 gpm pressure washer. The special adaptor end has an included 0 degree nozzle sized for the output of the presssure washer. In use it spreads out quite a bit once it leaves the screw in cone end. The city water i hook up to is very cold coming from lake superior, say 45 degrees. I understand the peening effect is conducive to distortion, but after using it on three projects now using sand and blackjack and no distortion all i know is it works great and i have no complaints. To be honest i never saw the trailers that the guy waterblasted. 2 individuals with the same results, i can't say for sure. I clean my stainless steel expanded metal barbeque grill platform and takes the baked on food of in seconds and looks new, set the platform down into it's recess and it lays flat. A friend had his rearend out of his olds on jackstands and in 15 minutes and 4 bags of blackjack i had the whole thing down to bare, backing plates and all and removed rust scale 1/4" thick in spots. In use i stay back about a foot from the surface.

[Port&PolishMan]

Originally Posted by 68c10airstream

I was initially lured in from a guy purchased a pallet of sand. I asked him what he used that much sand for? He said some of his buddies are contractors and pull enclosed trailers and the road salt destroys the paint job in no time. I remarked that if he sand blasts and hits the aluminum body near the frame it would be an ocean of waves from distortion!! His remark was "not at all". I asked what he was using? He said an attachment for a pressure washer! I went to youtube and searched it out, saw videos on it, google searched a vendor and matched my 3800 psi 3.5 gpm pressure washer. The special adaptor end has an included 0 degree nozzle sized for the output of the presssure washer. In use it spreads out quite a bit once it leaves the screw in cone end. The city water i hook up to is very cold coming from lake superior, say 45 degrees. I understand the peening effect is conducive to distortion, but after using it on three projects now using sand and blackjack and no distortion all i know is it works great and i have no complaints. To be honest i never saw the trailers that the guy waterblasted. 2 individuals with the same results, i can't say for sure. I clean my stainless steel expanded metal barbeque grill platform and takes the baked on food of in seconds and looks new, set the platform down into it's recess and it lays flat. A friend had his rearend out of his olds on jackstands and in 15 minutes and 4 bags of blackjack i had the whole thing down to bare, backing plates and all and removed rust scale 1/4" thick in spots. In use i stay back about a foot from the surface.

Your Material is Totally Different and I'm sure Your NOT Measuring as the Tester Did !

I have used Sand and Glass Bead - on lower - Air Settings - Damage may happen from "Over Working" an Area ..