External Undercoat Removal - Store bought dry ice

[tdw28210]

As part of my woefully under-documented 77 hot rod project. I currently have been challenged with removing the EXTERNAL undercoating. I already got the internal stuff out using mostly a hand scraper with a little bit of air scraping. The external stuff is MUCH nastier and gooey-er. I've read a few posts that recommended using a torch and scraper. I tried it. It works - sort of - but leaves lots of residue and makes some pretty nasty smells and who knows what kind of toxins were released. I tried it for about an hour and managed to clear and 1' by 2' area with a lot of residue. I was NOT digging the process and decided to take a different route.

One of the guys that comes to our monthly Cars and Cappuccino gatherings and drives an older BMW and suggested dry ice. NOT dry ice blasting, but grocery store variety. He said if you let it freeze the undercoating, you could scrape it off fairly easily. I checked out a couple videos on Youtube and decided to test the process myself.

NOTE: My car is on a rotisserie and that is key to this process. You need to let the ice sit on the undercoating. Without the car being upside down I don't think this work.

Tonight I trucked down to the local grocery store and bought $5.00 of dry ice. I smashed it its bag on the driveway, put on a face shield and gloves and rotated the car to an upside down position. I poured on about $2.00 worth of dry ice and waited. After it sat for 10 minutes or so I smacked the area that had the ice on it lightly with a framing hammer and scraped. Guess what? It works! I was pulling off 3 and 4 inch pieces with relative ease.

I know the rotisserie will prevent a lot of guys from doing this, but if you have one this may be the route to go. Based on my experiment tonight, I figure I can complete this job for about $60.00 in dry ice and 2 hours of time.

Good luck and hopes this helps.




Here are some chunks of undercoating sitting on a step ladder.

[Bob Kontak]

Get a needler at Harbor freight.

Compact Air Needle Scaler

There is a bigger one. Get that one.

[rennch]

Needle Scaler in action. Wow! https://www.youtube.com/watch?v=yJRf6zrulC4

[al lkosmal]

holy fuch!!!!! must have this.

[Vereeken]

This works.

i was talking to Lakewell guy (from the interior carpets for our 911s) and they like to do interiors in the winter.

They leave the car overnight when it freezes and the next morning the stuff -be it in or out of the car- comes off very easily with a hammer and chisel.
Heat seems to be more of an enemy i this case.