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Technical Any painters familiar with dustless blasting?

Discussion in 'The Hokey Ass Message Board' started by metalman, Dec 7, 2016.

  1. metalman
    Joined: Dec 30, 2006
    Posts: 3,280


    I guess this "dustless" blasting is the newest rage for stripping cars since we have several new companies showing up doing it. I've never had to deal with one done this way before but I now have a customers car that was stripped this way. From what I understand they mix water with the sand while blasting but they put some type of chemical in it to keep it from rusting right away. I guess they also spray the car down with the same chemical after they are done. My questain is do I need to treat the metal with anything before I start priming? The blaster said just hit it with a scuff pad and I'm good to go but not sure I trust him, especially with a high end paint job I'll be responsible for if it fails.

    If nothing else it sure leaves a mess, there is sand stuck in every crevices, going to take a lot of time cleaning it out or take a chance of it blowing out somewhere while painting. Not sure I'm sold on this way of stripping.
  2. i just got a car in for the first time that the owner had "dustless blasted". we ended up cutting the rockers off and changing them instead of repairing the rotted end. both rockers were full of a sand "cement" that would not or would have been a job to blow out of. i wasn't impressed.
    i always sand blasted metal down with 80 grit on a DA sander to get the "fuzz" off and clean it.
  3. metalman
    Joined: Dec 30, 2006
    Posts: 3,280


    Yeah, dry sand you can blow out but this sand is stuck, cement is a good description.
    I know how to deal with normal sandblasting but my concern is whatever chemical they sprayed on it. I don't want a adhesion issue or a chemical reaction with the primer due to the chemical.
  4. I was told they use crushed glass more then the sand.
    They dry blast the interior so they can blow out the crevices.
    From experience...they cannot get it all out....
    "Rust inhibitor needs to be mixed with the blast water in a 1/100 ratio, which is about 7 oz for every 5 gallons. This prevents chlorides from being embedded into the metal during blasting, but after blasting is complete you still need to give it a final rinse. We like to use a fertilizer sprayer that screws onto a water hose and measures out the selected amount of rust inhibitor per gallon. The one we've used is on the left, and you can buy it from Home Depot. An even easier solution if you own one of our Mobile units is to add the rust inhibitor into the water tank, and rinse the metal with our superfast water pump and a hose. After the rinse down it’s important to make sure all the standing water is removed from the metal, so that it can air dry. We use an electric leaf blower for this. As long as nothing recontaminates the metal (water, dew, body oils, etc.) rust will stay away for up to 72 hours. It is a good idea to try to prime the metal as soon as possible after blasting" mmmmm, nothing about prepping for pimer....

  5. 0NE BAD 51 MERC
    Joined: Nov 12, 2010
    Posts: 1,473

    0NE BAD 51 MERC

    I do not like the sound of this stuff . When I still had the big shop I had a commercial plastic media blasting booth system and cleaning up that was bad enough . Material got into every nook and craney. I can not imagine what adding water would do. And no matter what you use to strip , the metal still needs to be sanded clean with 80 to 120 grit and wash down repeatedly with wax and grease remover or acetone . A scotch brite by hand I don't think would clean the residue off enough for good primer adhesion . Good luck Larry
    RATRODCHEVY likes this.
  6. slobroy
    Joined: Jun 22, 2009
    Posts: 360


    Had a supplier tell me to use Ivory soap when washing off the bare metal before priming.
  7. I'm not impressed with it either. Had a T body done and there was muck stuck in all the hard to reach areas. Took days for it to dry out inside the shop
    Haven't got to the bodywork stage yet, so I'm curious about the metal cleaning as well..
    39wagon likes this.
  8. metalman
    Joined: Dec 30, 2006
    Posts: 3,280


    Kinda a follow up. I will NEVER, EVER have anything blasted with this process again. They say the advantage of the water is dustless plus it prevents warpage by keeping the metal cool. NOT, warped any panel they hit both sides of, it's no safer then conventional sand blasting.
    Cleanup is a mess, spent 3 hours blowing, vacuuming the sand. Still managed to have a clunk blow out of somewhere into the final paint. Guess what... you can't sand the dirt out, it's ground glass and it's tougher the your sandpaper! Have to strip and start all over.
    Just as I was cussing the job I had a body shop send me the doors to a 40 Willys coupe they are doing. The dustless blaster (different blaster then I used) had warped the doors so bad they couldn't repair them, sent them over so I could roll out some new door skins.
    Just a warning to you guys.
    loudbang, RMR&C, tb33anda3rd and 3 others like this.
  9. thanks for confirming what i had thought.
    loudbang likes this.
  10. texas red dodge
    Joined: Feb 11, 2015
    Posts: 11

    texas red dodge

    two for two for me,two diff cars two diff outfits,same warped all two hell, no more for me
    loudbang likes this.

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