Undercoating removal

This may be posted in the wrong place so if it is please move it to the proper forum.
After getting my tub up on the rotisserie I found gobs of hardened undercoating. I did a search and found plenty of discussion on undercoating but none on removal. What is the best way to remove undercoating???
As always, thanks for the help.
Tommy

 

Sandblasting works for me

 

Torch and scrape?

 

Careful with the torch. I set fire to a truck that way once! Breathing the fumes wouldn't be too good for you either.

Maybe a heat gun...

 

I remove old bondo with a map gas bottle and it works great. Should work the same for undercoating. When most of it is off finish up with solvent.

 

sandblast.....

 

Going against the grain here but I made a tool out of an old wood chisel with a truck shift knob for a handle. scraped off fairly easily once you get the hang of it. no fire hazard, no warped metal. the small leftovers and thin areas come off very cleanly with a wash of WD-40

 

I'll ask the sandblaster Monday but I wanted to do the body work before sandblasting. I noticed that some would come off with heat when I was cutting the tub bolts with a torch but I'm afraid I might warp the metal or worse have a big fire with the torch. I'll try a heat gun and make a stronger scraper tomorrow and go to the torch if I have to. Some of this stuff is pretty thick.
Thanks to all,
Tommy

 

believe it or not the thicker it is the easier it is to scrape off cold.

be careful sandblasting it off, the added blasting time per surface area will increase surface hardening of the medal and warping

 

tried it, tended to heat up the undercoat and fill up the wheel, then sling chunks all over the place

 

Don't sandblast after bodywork. It will screw up all of the body filler. I sandblast my tubs first. That way I have a clean surface to weld to and know the condition of every area. Then I do the metalwork. After all the welding and grinding is done I sandblast those areas again, then start bodywork.

 

x2. Don't need to set it on fire, just soften it up. I used a proprane torch and the tip that kinda spreads the flame out in a fan type pattern. Do it outside if you can. I didn't but prolly should have.

 

By bodywork I should have said metalwork. I work outside and don't want to contend with rust on freshly cleaned areas. I assume I would need to prime ASAP after sandblasting and if I sandblasted first it would mean priming over rotten areas an then cutting them out later. I do, however, like the idea of working with clean metal.
So far this undercoating has turned into a lot of hard WORK.
Tommy

 

I experimented this afternoon.
The WIRE WHEEL got the undercoating soft and just smeared it around.
The SCRAPER did a passable job but took MUCH elbow grease and was not handy in tight spots.
PAINT REMOVER and WD40 may be OK for clean up but they are VERY messy and no good on heavy coating.
The WINNER (at least for today) is the ROSEBUD TORCH and PUTTY KNIFE. Modest heat made the undercoating soft and easy to remove at least to the point that a sandblaster can do the rest without much added effort.
Thanks for all of the suggestions.
Tommy