How to remove Galvanizing on Auto Sheetmetal?
RSS | Subscribe | Contact Us | Advertise | About Us
Results 1 to 10 of 10
  1. #1

    How to remove Galvanizing on Auto Sheetmetal?

    I'm replacing body panels on a car which has galvanized coating on the sheet metal from factory. I'm having a difficult time finding the right method to remove the coating. Twisted cable wire wheel on an angle grinder is ovaling the spot welds which were drilled out and doesn't seem to remove all of the coating. I tried vinegar which does nothing and phosphoric acid which bubbles a little but after several re-applications doesn't appear to remove the coating either. Should I just brush on muriatic acid or is there another way?

    Thanks

  2. #2
    Join Date
    Apr 2006
    Location
    Soda springs,Id
    Posts
    4,285

    Re: How to remove Galvanizing on Auto Sheetmetal?

    A fine grit flap disc will remove it without removing much iron.
    Mike
    Ol' Stonebreaker
    "Experience is the name everyone gives to their mistakes"

    Miller 175 mig
    Miller thunderbolt ac/dc stick
    Victor O/A setup
    Makita chop saw

  3. #3
    Join Date
    Dec 2015
    Location
    Western New York State, USA
    Posts
    1,711

    Re: How to remove Galvanizing on Auto Sheetmetal?

    Quote Originally Posted by Tigers View Post
    I'm replacing body panels on a car which has galvanized coating on the sheet metal from factory. I'm having a difficult time finding the right method to remove the coating. Twisted cable wire wheel on an angle grinder is ovaling the spot welds which were drilled out and doesn't seem to remove all of the coating. I tried vinegar which does nothing and phosphoric acid which bubbles a little but after several re-applications doesn't appear to remove the coating either. Should I just brush on muriatic acid or is there another way?

    Thanks
    .
    why remove zinc coating ?? silicon bronze "everdur" is used to tig and mig galvanized steel as it doesnt mind a little zinc mixed in and does the least damage to the zinc at the weld area. also silicon bronze melts before steel. in theory you are not melting any steel but are brazing it. been used by tin knockers making galvanized ductwork for a long time. in the old days they did not even used a tig torch but used a single carbon electrode with a dc welder.

  4. #4
    Join Date
    Oct 2016
    Posts
    92

    Re: How to remove Galvanizing on Auto Sheetmetal?

    err.... Ok, so there's a lot of potential for... variations here.

    On new panels, if they didn't already come with the spot weld holes, you should be using a punch to do it. Its safer and doesnt leave as sharp an edge on the back side
    Its generally not necessary to remove any part of the coating. Its what protects the metal, especially at the weld area. Theres enough of an exposed lip from the punch. The vapors are what will get you so use proper precaution

    2. 3m roloc discs are the way to go. Pretty much ANYTHING on an angle grinder is over kill for panel work. ( i say pretty much, but there are exceptions to statement). Angle die grinder with roloc adapter is how I was taught and how I learned. Works like a champ, and nearly impossible to gouge the metal as you described.

    If you do decide to remove the galvanizing, you should at least replace it with weld through primer.

  5. #5
    Join Date
    Jun 2016
    Location
    Not there
    Posts
    2,460

    Re: How to remove Galvanizing on Auto Sheetmetal?

    Galv auto body ? I'm old and don't work on things less than about 30 years... Get after it with sil-bronze I suppose. That would be my first shot.

  6. #6
    Join Date
    Oct 2016
    Posts
    92

    Re: How to remove Galvanizing on Auto Sheetmetal?

    Most cars after 1987 came with galvanized bodies and panels. Most panels were spot welded after that, but they just used a spot welder, not mig. Mig is the approved way for most after factory crash and rust repairs. This is why you see a lot more cars made after 1987 than before 1987. (or roughly there abouts). You might also remember seeing a bunch of GM cars that look like the paint was peeled off, but no rust. That was late 80's early 90's GM paint tech. they had issues with adhesion between the paint and the factory galvanizing.

    This article mentions the problem

    https://www.washingtonpost.com/archi...=.9b584eba7d4f

    oh, and 1987 is 30 years already. lol. You also wouldnt be very safe with sil bronz as it isnt an approved repair for unibody cars.

  7. #7
    Join Date
    Jun 2016
    Location
    Not there
    Posts
    2,460

    Re: How to remove Galvanizing on Auto Sheetmetal?

    Quote Originally Posted by madmax718 View Post
    Most cars after 1987 came with galvanized bodies and panels. Most panels were spot welded after that, but they just used a spot welder, not mig. Mig is the approved way for most after factory crash and rust repairs. This is why you see a lot more cars made after 1987 than before 1987. (or roughly there abouts). You might also remember seeing a bunch of GM cars that look like the paint was peeled off, but no rust. That was late 80's early 90's GM paint tech. they had issues with adhesion between the paint and the factory galvanizing.

    This article mentions the problem

    https://www.washingtonpost.com/archi...=.9b584eba7d4f

    oh, and 1987 is 30 years already. lol. You also wouldnt be very safe with sil bronz as it isnt an approved repair for unibody cars.
    Thanks for the reminder. I bought a brand new 1999 GMC van and the paint peeled off the roof in a couple of months. GARBAGE.
    Galv is garbage for most everything. I refuse to build with it.

  8. #8

    Re: How to remove Galvanizing on Auto Sheetmetal?

    I'll give the roloc discs a try since it sounds like abrasive is the way to go.

    I'm using TIG to join the panels since that's what I've got. Weld through primer will mess with the arc quality. Any suggestions how to protect the metal inside the joint?

  9. #9
    Join Date
    Jun 2016
    Location
    by a resevior in north central ar.
    Posts
    160

    Re: How to remove Galvanizing on Auto Sheetmetal?

    just as a note to the gm, ford, chrysler paint was that all the colors effected were clear coat colors. the factory paint manufactures didn't put enough uv protector in the clear and and the sunlight (uv) would go thru the clearcoat and the color. the color was so thin because of EPA regulations. the uv's would then attack the primer which would then chaulk up and and cause the color and clear coat to lift. you never saw and rusty cars, just cars running around with gray primer and peeling paint. after the sun and years of this, the primer gradually would come or wear off to the metal, then it would rust.

    as far as removing galvanizing, 80 grit on a grinder or rolock disk worked for us.

  10. #10
    Join Date
    Sep 2008
    Posts
    177

    Re: How to remove Galvanizing on Auto Sheetmetal?

    You also wouldnt be very safe with sil bronz as it isnt an approved repair for unibody cars.
    You might want to read up on UHSS and silicone bronze
    http://www.repairerdrivennews.com/20...ght-demand-it/
    http://www.bodyshopbusiness.com/mig-...rning-process/
    Last edited by 131re; 06-14-2018 at 07:02 PM.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
RSS | Home | Penton Media | Contact Us | Subscribe | For Advertisers | Terms of Use | Privacy Statement