Car is heading for the stripper!

I want to acid dip my comet. The problem is I have to remove the 46 year old undercoating or pay $95.00 per hour for some kid to do it. Any of you guys had any luck removing this stuff? You think a heat gun would warp the metal? How about bead blasting the areas of undercoating and then send it to the strip tank. Chemicals?
The last time I did this, my bill was a additional grand! for the strip job.

Thanks

Tom

Bead blasting probably will not cut through the undercoating. Do the hot torch thing with a scraper or putty knife.

Charlie

I don't know how simular this stuff is sound deading insulation. A heat gun and a putty knife is the best way to remove that stuff.

I guess I will get a propane torch and a scraper. I hope i don't warp the sheetmetal.

Tom

I think I did some a while back and I used a High temp hair like dryer, and a scraper...


Randy

Yellow propane torch and scrapper.Thick set of rubber gloves.red scotch brite,and a gal of laquer thinner.Scrape as much off as you can with the torch.You want be able to get in the cracks.Then use the scotch brite .an old bowl,dip the scotch brite and scrub like hell.Your metal will shine just like new metal,and be ready to dip.Hope this helps.Michael

Why acid dipping vs say any form of bead blasting?

The one major drawback to acid dipping is rust can grow back quite quickly in hidden areas of the body. Especially between multiple layers of spot welded sheetmetal. Acid dipping is less of a problem on bodies for full chassis cars where there is almost no inner body structure left inside the shell. This leaves almost no hidden places or places between layers of sheetmetal for rust to grow. If you go with acid dipping choose a company wisely. They are NOT all the same, have the same experience/knowledge, or use the same procedures. Some are good at what they do, and some are hacks. Do your homework first........

Ask the company you want to use if they also coat/dip the acid cleaned body shell in a preservative afterward to prevent the inevitable (almost instant) flash rusting that happens after acid dipping.

If they coat/dip with any number of oil based metal preservatives after acid dipping, you will have a limited amount of time to get a coat of paint on the bare metal before rust will start.

If they use a phosphate etching preservative dip after acid dipping you will have some more time to get some paint on the shell before rust starts. And the phosphate coating usually gives the metal a good "roughed-up" surface for paint & body filler to attach to.

Years ago the first company I decided to used to acid dip my Mustang shell was a major mistake, I didn't know they were idiots & hacks. Instead of using a platform to get the body in/out of the dipping tanks I found out later they just used chains wrapped around parts of the body that did some scarring damage to the skin. But the major kick-in-the-balls was they DROPPED the body on the ground twisting the shell & warping/rippling the roof at some point during the dipping process when a chain came loose. When I picked up the shell something just didn't look right. But I just couldn't put my finger on the problem cuz the acid cleaned metal shell was a brilliant white color which helped mask the ripples in the roof line. When I later discovered the damage they first tried to deny it ever happened, then finally admitted they dropped it. But their attitude was "so what, fuck off".

Blasting is a much better option IMO

The 65 fastabck I built was acid dipped. Your right about the rust sneaking out of the spot welded panels. It took about 2 years of being bare metal and in my garage for the rust to start creeping out. I scrubbed it really well with etch and knock on wood it hasn't came back.
It was so nice to work on a 40 year old car that looked just the way it did on the assy line. It made my job alot easier having all that crap off it.
I know it doesn't add up to much weight reduction but that mustang body was so light after it was acid dipped. I think this was common practice in the 60s along with the aluminum panels, etc..??
I heard some people have the bead blasting material come out during the painting process so they both have their flaws I guess.
I watched them take a fork lift and slide the forks thru the door opening and pick it up that way. Scared the hell out of me.
The final bill was over 2 grand for dipping. Crazy! Most of that was some kid scraping off the undercoating and charging 95 bucks a hour.
If this shell doesn't come out as nice I will try the blasting route. Another reason I kind of dislike bead blasting is it's hard for the guy to get all the places with the blaster. I want the thing spotless. Fussy I guess.

Tom

747JetMech wrote:I know it doesn't add up to much weight reduction but that mustang body was so light after it was acid dipped. I think this was common practice in the 60s

Well there is some difference between a short acid dipping just to get to fresh bare metal (and a slight amount of weight loss), & a long dip to thin the body shell's skin a decent amount to reduce weight even more like the Pro Stocks did years ago.

The 1st shop (that screwed up my Mustang body), never heard of dipping to thin the metal skin (go figure), all they knew about was dipping just to get to bare metal. The 2nd shop I used (that re-dipped the repaired shell & phosphate coated it) knew about both procedures. They never mentioned if different types of acids where used for short simple dip vs a longer dip to thin the metal. But they did mention that dipping to thin the metal took a lot longer to do, and was difficult to do correctly. This was because they had to constantly monitor the acid's progress so they didn't remove too much metal and destroy the shell.

I remember reading an old article where one Ford P/S team's car (Roush or maybe Dyno) had doors dipped so thin by mistake that they had to add back in some reinforcement (something like fiberglass or foam) inside the door. They were worried it was so thin someone could easily push a finger through because the sheetmetal was so thin.

a better way to do it is Sodaa blasting the body it does not distort the metal like beads or sand, also it cleans very nice....


Randy

the Coug wrote:a better way to do it is Sodaa blasting the body it does not distort the metal like beads or sand, also it cleans very nice....


Randy

Recently I read about some paint adhesion problems after soda blasting. Unfortunately, I can't remember where or when.

cletus66 wrote:

the Coug wrote:a better way to do it is Sodaa blasting the body it does not distort the metal like beads or sand, also it cleans very nice....


Randy

Recently I read about some paint adhesion problems after soda blasting. Unfortunately, I can't remember where or when.

thay use wallnut shells now

if you live where its cold out its easier to scrape it off when its cold. or i used gas and a scraper, chisel, and a big screwdriver