I just used an air needle scaler to remove undercoating and years of hardened road grime on my frames and pans. Wow that is a great tool. I bought the mini scaler and it will remove a 1 foot square section of undercoating in about a minute. Just thought I would pass it along.

Yes they will but they also do a job at texturing your sheet metal finish as well. Have you tried a steam cleaner?

They work amazing i felt the same way after i discovered one. I had to tell the world!!! No more torch and scraper

You can rent these steam cleaners? I saw the pics that looks like alot less work.

Yes you can rent one at most any large rental yard. Rent one in the 1,500-2,000 psi range with temps around 200 degrees and you'll be set.

INDEED! I have also seen the light with this tool. I needed to remove scale, surface rust, dirt, etc. in the little nooks and crannies of the fenderwell on my cuda.
I didn't want the mess associated with sandblasting.
I was warned not to use these around sheetmetal, and I could see that if you are a butcher - but with a careful hand and using finesse this tool is awesome. I also had a spare set of needles to play with - new sharp, square edged needles do leave divets, but rounding the needles off on a grinder helps with that.
Wear ear protection though - very noisy!
Here is the area that was repainted - perfect tool for getting the crap out of the crevices.