Sandblasting. Wet or Dry? Which to use. [Archive] - Chevelle Tech

: Sandblasting. Wet or Dry? Which to use.


ChevelleL88
Jan 2nd, 03, 5:02 PM
Hey guys. I am renting a sandblaster this weekend to clean up my Front end before i put my POR15 on. I was wondering which is better, wet sandblasting or Dry sandblasting?
I will be doing the trunk too to get the pesky rust behind the rear windows and along the top. How hard will it be for me to get the sand out of the trunk once im done blasting it?

I just need general tips and help on this. Thanks everyone.

-Sincerely Eric Crain-

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-1970 Chevelle Malibu 427-
-1975 El Camino Classic 350-
~American muscle cant be beat~ Please sponsor me :) NeoSSChevelle@Hotmail.com

sevt_chevelle
Jan 2nd, 03, 7:16 PM
I have to ask what is WET sandblasting and where did you ever hear such a term? The slightest amount of moisture will plug up a blaster. You ever go to the beach and pick up wet sand with your hand?, theres no way that will ever go though a nozzle.

Sandblasting will throw sand all over your car inside and out. It will be in the dash under the seats in every nook and cranny. You will need to mask off anything that you dont want sand to enter cause it will if you dont mask. Prepare to send several hours with a vac and air hose removing sand. If you dont remove all of it, over time it will absorb moisture and hold it resulting inrust.

Also sand blasting IS NOT meant to be used on exterior panels like fenders, hoods quarters. The friction of the sand agaist the metal as it hits generates so much heat that will wrap and disfigure the metal, so fast you wont even see it happen and by the time you do its too late. Sand is fine for metal like frames and floorboards but not exterior panels PERIOD.

One last thing make sure you wear some type of mask. Breathing in that silica can be very harmful to your lungs so wear a mask to protect your lungs, a full face hood willnt provide the protection get some cheap masks that cover the mouth and nose...Eric

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1970 chevelle
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70isfine
Jan 2nd, 03, 8:14 PM
Wet sandblasting is more like powerwashing,where sand is mixed in with the water for abrasive purposes.I've seen it used in industrial applications like bridges or on sidewalks.Flash rust could be a problem.Baking soda works great in my blaster,but i haven't been able to find a local place to buy large amounts of it.I would stick with dry sand if i were you,just get a good respirator.

Frank G
Jan 3rd, 03, 4:05 AM
I would strongly recommend you not sandblast in the trunk, no matter how good a masking job sand WILL work it's way into the interior. If you're planning on using POR-15 in the trunk than you can just wire wheel the rust and scuff any remaining paint to do a good job. Also, if you are blasting around the windows mask off the glass because the sand will etch the surface, we're talking permanent destruction here. Overall, just be careful with the preparation and move slow. Good luck, sandblasting is not a fun job.

Frank

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1967 Chevelle SS 396

72SSAbody
Jan 3rd, 03, 4:51 AM
<BLOCKQUOTE>quote:</font><HR>Originally posted by 70isfine:
I would stick with dry sand if i were you,just get a good respirator. <HR></BLOCKQUOTE>

Stay away from the sand due to silacosis (sp?) of the lungs. Yes, I see the recommendation of the respirator, but there is an alternative.

I've used Dupont "StarBlast" with great results. Its pretty damn cheap too at around $4/50lb. bag. Search the yellow pages to find a distributor.

And use that respirator!! Anything, but air will hurt your lungs in the long run!!

Joe



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torquefactory
Jan 3rd, 03, 6:23 AM
i must agree that sandblasting an exterior panel can disfigure it. but there is an alternative. Crushed walnut or almond (either or) shells can be used and will not hurt the panels. it leaves a nice textured metal that leaves good painted results

ChevelleL88
Jan 3rd, 03, 7:33 AM
Where would I go about getting crushed Almond or Walnut shells? How fine should the shells be?

I was also thinking about just using a chemical stripper to take off the old paint and then shooting primer, wet sand it and shoot agian.

Also im going to take some pictures tomorrow of the damage on the drivers side rear quarter panel and i will get the pictures developed somtime next week. I am going to post the picts and ask how much you guys think it would cost to have that area repaired. Maaco charges $50 an hour. And the guy at the shop said "Maybe 10 hours" which means 20 hours by their standards http://www.chevelles.com/forum/biggrin.gif
$1000 dollars would be insane just to fix the quarter panel. I could get the rear peice i need from NPD or GoodMark for $169 dollars and since im handy with a welder it would be an easy repair. The only thing is though that I really dont want to cut up the body. I would be willing to pay $500 - $700
but surely not $1000

My rear bumper is also squished nearly flat on the drivers side. Is there anywhere that has a press or anything where I can get the bumper re-molded back to its original shape?

Thanks guys, your all a big help.

-Sincerely Eric Crain-

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-1970 Chevelle Malibu 427-
-1975 El Camino Classic 350-
~American muscle cant be beat~ Please sponsor me :) NeoSSChevelle@Hotmail.com

MAXX2
Jan 3rd, 03, 9:55 AM
A painting contractor friend of ours uses the wet sandblasting method to remove paint on old houses. It works great, as it doesn't pit the wood near as bad as it would if he used it dry.

Don't know the name/manufacturer of his sandblaster, but we have seen it in action.

Awesome!

We sandblasted our firewall before we sprayed on the POR 15 Silver (Use Your Respirator!!!!!). It didn't warp anything, but it didn't really matter anyway, as we covered it with our 2 piece aluminum firewall.

The body and frame were beadblasted.

Hope that answers some questions.


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Team Members Forever #341

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jeff martin
Jan 4th, 03, 12:21 AM
DRY ICE......This is the solution. Media blasting is a very diry process, you are going to get sand/plastic/glass all over the place no matter how hard you try. If you are going to blast the inside of the trunk the media is going to end up on the inside of your car and find its way into place's you wont be able to clean. If you cant get it all and it builds up it will have the tendancy to retain moisture and aid the rusting process........ But if you were to use DRY ICE, all that is going to happen is the ice will melt and take its normal gaseous form of carbon dioxe. No moisture is left behind what so-ever, and no residue like some plastic media's will. No moisture you say.... yes, Dry Ice is just carbon dioxide at a tempature of -260f at wich it takes a solid form. You can get dry ice in block, pellet and rice form. Ask around at your bottled gas supplier, and they should be able to help you find dry ice. It might be a little more exspensive then a plastic media but well worth it, in the fact that there is no clean up required.
-Do not use almond or walnut shells, I have been told and read many of times that this process is dangerous due to the flamability of the dust created by the nut shells. It might not happen often but there is still the possibility, Iwould not suggest this method!
Hope this helps

Mister Darling
Apr 30th, 10, 5:53 PM
:DDRY ICE......This is the solution. Media blasting is a very diry process, you are going to get sand/plastic/glass all over the place no matter how hard you try. If you are going to blast the inside of the trunk the media is going to end up on the inside of your car and find its way into place's you wont be able to clean. If you cant get it all and it builds up it will have the tendancy to retain moisture and aid the rusting process........ But if you were to use DRY ICE, all that is going to happen is the ice will melt and take its normal gaseous form of carbon dioxe. No moisture is left behind what so-ever, and no residue like some plastic media's will. No moisture you say.... yes, Dry Ice is just carbon dioxide at a tempature of -260f at wich it takes a solid form. You can get dry ice in block, pellet and rice form. Ask around at your bottled gas supplier, and they should be able to help you find dry ice. It might be a little more exspensive then a plastic media but well worth it, in the fact that there is no clean up required.
-Do not use almond or walnut shells, I have been told and read many of times that this process is dangerous due to the flamability of the dust created by the nut shells. It might not happen often but there is still the possibility, Iwould not suggest this method!
Hope this helps

Jeff, this is a fantastic idea and it definately helped me a ton. Dry Ice is the perfect thing to blast with for any purpose because CO2 is never actually a liquid; it changes from a solid straight to a gas since it is one of the few substances that sublime (I believe another is iodine). This means no moisture/liquid ANYWHERE so no possibility of rust while using this and no clean-up. Haha there is a little chemistry for you :D!

Luv_My_Chevelle
Apr 30th, 10, 8:05 PM
Wow I never heard of Blasting with Dry Ice how well will it clean I would like to do my frame Will this method clean it sufficently