Undercoating removal.. is sandblasting the best?

Short of hiring someone to do the work, there is no easy way to remove all the undercoating from a car body. I have done it twice - once on a roto-body and once on my back. The job is a messy one for sure. The roto-body was the way to go, as, you don't get dirty doing the job. It also makes the re-paint job much more easy and thorough. Painting upside down is about as much fun as welding upside down. In the interest of getting the job done I would just suit up and get to work and set goals for each "session". Before too long it was all done and the money expense was minimal, too. Heat and scrapers and paint thinner with rags were the way to go for me. The paint thinner gets sprayed onto the tar/ uc residue and after a soak time will wipe right off. Just wear a mask, gloves and some old clothes or a tyvec suit and have at it. It's a very unforgiving job and nobody seems to care, but, worth it to me.

 

You can use blocks of dry ice to freeze the undercoat, making it easier to chip it off. This is not to be confused with dry ice blasting, which is like sandblasting.
I've even seen a post here where someone recommended using a CO2 fire extinguisher to do the same thing.... freeze the u.c.

Most solvents should remove the residue. Mineral spirits and Wax and Grease remover are other options.

 

Do a good job, but DONT sweat the details, once all together you’ll never see it and you’ll soon forget about it

 

Not to be a devil's advocate but, Is it really important to remove the undercoating? My car was Ziebart undercoated when it was new and it's still in place including the plugs that were installed throughout the body after the stuff was injected into the body and frame. The car has been "frame up restored" and all the floor panels and sheet metal is original and rust free. So, why would I want to go to all that trouble and mess to remove it? Is there likely to be rust under the undercoating?

 

Yeah, that was my plan to leave it but when I removed the frame to have it blasted and painted... I figured why not as not every part of the car was undercoated and there was some rust here and there. The car will never be apart like this again but yeah I probably should have just let it be as it's not going to be a show car but I'm here now.

 

Slowly walk away...let's think this over. You didn't have an issue with the undercoating. You are not finding rust under the undercoating you've removed. My 2 cents - fix the rust you found (wire brush, ospho, prime, paint) then recoat everything with new undercoat - or at least where it's not coated. Use some good stuff like:
https://www.roversnorth.com/parts/rnw5001_waxoyl_gravelgard_500_ml_16_9_oz_aerosol

 

Well, it's done. About 10 hours with the heat gun scraping. It left behind residue and paint thinner was going to be another big chore and wouldn't get in in all the crevices. Had a local guy come out and blast the bottom for $275. I know I'll find remnants of sand everywhere later but it's now painted... not an awesome paint job, a few runs....Now wait a couple days and will drop it back on the frame.

Pics
1- what I was dealing with
2- after the scraping
3- after the sand blast
4- painted.

 

Good job!
Messy isn’t it!
There’s no “clean” way to do that, but it feels good when it’s done!

 

Thank

Thanks, yeah, huge mess but so glad it's done.

 

I use an air grinder with an 8” hook it back up pad with an 80 grit disc to strip cars/panels at work, it’s frickin’ messy! But it’s either that or a DA, which takes FOREVER, OR paint stripper which is even messier!
But I feel good ( tho I’m filthy) when I’m done

 

Looking good, nice work....

 

Your floor is in great condition! I have a lot of rust under the floor protection..
Well done!

 

Did you purchase all that equipment ? Or rental ?

 

I was able to buy a used 20-year-old professional machine cheaply with only 53 hours and sold it on after use in a short time without any loss.

I rented the compressor.

 

Thanks , 20 years , we’re just recently seeing them.

 

Tip I got from a Camaro message board yrs ago, tried it worked very good, got 80% off. Buy a cheap garden sprayer, fill it with kerosene, spray undercarriage once, then again 24 hrs later, then let it soak for 24-48 hrs. Rent a steam jenny to wash it off. Worked well, other than idiot me didn't think about what the kerosene would do to my asphalt driveway.