Sandblasting sheetmetal

[Thomas DeBusk]

I have a '50's mopar with lots of surface rust. I'd like to sandblast, but have been warned that I could easily warp the metal by introducing too much heat. What can/should I do to avoid damage? Move quickly? Cool with a fan? Use a particular media?

Oops!Since this is a Jeep site, I should've said "Wag" instead of "'50's Mopar". Truth is I have one of each and both have lots of surface rust. The Jeep has lots on the hood. Motor heat burned off the paint. I realize the Wag is the one more endangered by sandblasting as it has thinner metal.

Thomas

[ July 16, 2002, 10:57 PM: Message edited by: Thomas DeBusk ]

[PhilSine]

Part of the problem with sandblasting is not necessarily the heat but the tiny pits the silica leaves on the surface of the metal. There is a process called bead blasting that uses tiny plastic beads that do not pit the metal.

Another alternative available is using a chemical stripper. I use this stuff called "Aircraft Stripper". It has worked for me in the past.

[Tad]

Make some calls in your area to companies that do media blasting. There are all sorts of alternatives to sand, like walnut and pecan shell blasting that produce less heat, warpage and pitting.

[OBX-AUTOMOTIVE]

HE,HE,HE..RIGHT!!! 1950S MOPAR...... SURE YOUR'RE GOING TO WARP IT :confused: ...HELL!! YOU COULD BUILD A WHOLE RICE CAKE...OUT OF THE TRUNK AND HOOD,OF THAT 50S MOPAR!!!..AND THAT WARP STUFF...I DON'T GET IT>>> LOT'S OF SAND-BLASTING UNDER MY BELT :rolleyes: I NEVER WARPED ANYTHING?? SURFACE RUST>>>DA IT!!!YOU WOULD.... SAND-BLAST PITTED METAL...THE IDEA IS TO REMOVE THE RUST IN THE PITS... TO REPAIR THE RUSTED SPOT!!!........ ....AND AS FOR PAINT REMOVER...WHAT A MESS!!! YOU EVER GET PAINT REMOVER IN THE DOOR...JAMS....NOT FUN!!!.... LARGE DA STRIPER...8" PSA 80gt WILL CUT IT AND YOU CAN CONTROL IT BETTER :cool: :cool:

[Ralph]

Ahhhhh, GEM, the voice of experience and reason!

Well, experience, anyway.

I went through 18 x 100-lbs bags of white silica blasting rust out of my truck. Not one bit of warpage, though I could imagine it happening with really thin sheetmetal. Also, sandblasting is not the most efficient way to remove paint -- sanding with 36-grit to chew out the thick stuff, 80-grit to wear through normal paint without leaving such deep grooves to fill in later.

Thomas Debusk, I don't know what facilities you have in your area, but I just picked up a hood and fenders for another IFSJA member (Narnia) from RediStrip (http://www.redistrip.com) , and the metal is so clean it looks like it just came off the stamping press! They charged $85 each for the wide-track fenders and $100 for the hood.

Today I'm on my way back there to pick up a set of wheels that were just dipped.

[ July 17, 2002, 07:15 AM: Message edited by: Ralph ]

[OBX-AUTOMOTIVE]

RALPH!!! YOU ARE 100% RIGHT.... BUT NOT EVERYONE HAS A REDISTRIP..IN TOWN! smile.gif smile.gif

[ClarkGriswald]

I agree with Gem you could probly sandblast if you are just carefull.

I have stretched out some metal with a sandblaster so I have exp with that but I have to say it was some pretty dang thin metal (was a metal medicine cabinet from an apartment, I ended up making a much nicer one from oak).

I would think that as heavy as our rigs are you could do it if you try not to heat up one area to much.

Ditto on the plastic media and other types but they are much more expensive than silica and most big places recycle that to be used 2 or 3 times i believe.

I just recently noticed that menards is selling ground up coal slag as a blasting media.. its cheap like silica .. anyone ever use this?? seems like it would be a little more gentle than silica.

Also If my memory serves me correct at around 90 or 100 psi silica will fragment a lot and the dust from that is real bad for ya.. make sure and wear a mask.

Anyway you could always do a test on a similar piece of metal (go to a junkyard and hack off a chunk of old car to play around with)

Oh yeah.. you could always just spray it down with heavy duty Easy Off oven cleaner hahhahaha.. (ok half joking on that one)

[ July 17, 2002, 12:53 PM: Message edited by: ClarkGriswald ]

[JEEPGUZZZI]

O.K., lets get our terminology straight. Bead blasting is done with glass beads, not plastic. Plastic media blasting is done at a low pressure and high volume- great for removing paint, but since the plastic is harder than the paint, but less hard than the rust, IT WILL NOT REMOVE RUST! I had this done to my Cherokee and am very glad I did. It is an economical way to strip the paint from the whole car, or sections of it, especially if it has a paint adhesion problem. I had mine stripped inside and out.
So, if I were you, I would plastic media blast the paint off, then you can use the grinder or sanding disc to remove the rust. Chances are, if you have surface rust, it has "spider webbed" under the old paint. If you don't get it all, you are wasting your time.

[Ernzo]

ROTFLMAO GEM!! I AGREE, ANY 50'S MOPAR HAS MORE METAL ON IT THAN A FLEET OF HONDAS!! EVER TRY TO DO BASIC BODY WORK ON A OLD DODGE? BREAK YOUR ARM.