Review of undercoating removal techniques.
 

After browsing through classic car forums, a few suggestions for chemical removal for undercoating came up. Eastwood sells a product, Aircraft Stripper, Flooring Mastic Remover and Easy Off oven cleaner. So while at a leading retailer I picked up some Oven-Off Heavy Duty, In the yellow can an preceded to burn my lungs into oblivion. No joke, I reached for a mask and so should you. I applied the product to an already clean underside of my 1980, which happens to be on a tip-over rig, and let the science work.

I returned about 4 hours later and the thicker undercoating really didn't budge much. The Easy Off seemed to have superficially softened up the undercoating but it dried up, so not much to say other than it did have an effect. More testing to follow.

Areas where the undercoating had a thinner application really did not stand up to the oven cleaner. Some mild scraping and extra coarse steel wool made short work of the undercoating. using a diluted degreaser and paper towels to clean up the surface has brought me to this point:

https://cimg9.ibsrv.net/gimg/www.rx7...db43bfe39.jpeg
https://cimg0.ibsrv.net/gimg/www.rx7...101c69b062.jpg

You can see the bottom rail for comparison. Still a lot of work to do, but going better than I thought. I will try the mastic floor remover next. I will not be trying Eastwoods product as of now. I would like to keep this as "hardware store" options.

Worth mentioning is using an oscillating multipurpose tool. It did work decent, but the blade I had was too wide and I broke it after a few minutes.

When finished I will coat with an epoxy primer or "Pitt-Gaurd"

Many thanks for the insight into your experience. Hopefully others will chime in with theirs?
What you did looks amazing. May I recommend POR15 undercoat products? I have used this on various 'touch-up' spots on my SA and the results have been excellent. Very (very) durable finish. I won't go on a rant here about how it works but the site is worth a look. If/when I get to your stage of clean-up, I will be using it to base-coat the metal.
por15.com
If you want to put some sort of chip guard and/or sound coating over top, do so. But for metal protection this stuff is fab.

Stu Aull
80GS
AZ

Thank you for the compliment, I am familiar with POR-15. The issue is I do not believe it to be a product that would serve me as I do not have any rust to paint over. As I understand it POR prefers to have a rusted substrate to bond to. The products I listed can be applied to bare metal and for a lower price than POR-15.

POR uses "Metalprep"

https://www.por15.com/POR-15-Metal-Prep_p_15.html

which is also a clean-metal etcher...
Yah, POR is not the cheapest, but in the YEARS I have used it on my SA, the stuff seems nuke-proof, so I was happy to pay a little more after all the sweat getting the surfaces of my car prepped.

Stu Aull
80GS
AZ

Stu, Congratulations on your "Super senior" forum member status! Your rotors add up to 30 years of Rotary knowledge and dedication. Richard, neat idea for a topic too.

Thanks for the insight!

Man it must be nice to have a lift, I couldn't even imagine...

If your undercoating is the old tar-based version, gasoline works very well.

I've also heard this as well, but it sounds relatively terrifying to try and accomplish. I'm stuck in a garage over the winter with heaters though, probably why it sounds so scary.

Your work looks great! I removed layers of old paint and undercoating on a '66 Mustang fastback with brushed on Klean Strip premium and a 3M Rust/Paint remover wheel and electric drill. If you let it sit about 5 minutes, it comes off with very little effort.

Your instincts are good -- I wouldn't try it in your situation.

Looks good! I would also recommend POR15 - amazing stuff. As mentioned, their Metal Prep give it a base to stick to. Nothing will get through if you follow the instructions properly :P

Update: Used a oscillating tool with serrated blade, cut though the thick undercoating rather well. Does leave a bit of a residue, but that would be easy to remove with chemical means.


Goo-Gone. Functional to clean up residue but will need to set for a few hours . Oven-Off seems more effective but was really harsh to work with. I'll be working on a larger area to test the Goof-Off later this week.

Would love some pictures of the products you used. And the active stuff in it so i can find a similar product in europe. I got a Miata im prepping for track use and need some way to clean it before welding. The RX-7 ended up being to nice to track xD

I'm about 75% done. Here is the product I have been using: https://googone.com/products/original-spray-gel/
The goo-gone does not evaporate quickly if at all. I was able to saturate the undercarriage and I then put aluminum foil over the top to "seal" in the goo. I would wait a minimum of 4 hours but I came back the next day and the undercoating just "melts" away in strips. You will need to do some laborious work in the wheel wells, but the goo-gone softens that up so it becomes a labour of love and not blood from a stone. Perhaps the oven cleaner would work faster, but it was rough on the lungs and caustic to the hands. (remember respirators and gloves) The Goo-Gone was citrusy and did not require safety gear.

Not sure what your plans are as a final product, but here's how I did my car with Hytech Metal Shield. You're welcome to tell them Ryan from RGHTBrainDesign in California sent you - Trish is your contact there. I've worked with POR-15, RedKote, LizardSkin, SecondSkin Audio, etc and this product ranks #1 in my usage. 3 Layers total after degreasing, alcohol, grinding, etc and it came out gorgeous.

Rust proof, Insulating Paint for Autos, Steel pipes and tanks
House Paint for Insulating Home, Roof, Siding, Ceilings, Walls, Attic Radiant Barrier Paint

Before:
https://scontent-ort2-1.xx.fbcdn.net...2a&oe=5AB5905C
https://scontent-ort2-1.xx.fbcdn.net...30&oe=5AC52E36


After:
https://scontent-ort2-1.xx.fbcdn.net...90&oe=5AC74F0E
https://scontent-ort2-1.xx.fbcdn.net...77&oe=5AB72617

Here's a short video of it (3:00):

Damned interesting product. Bookmarked.

Well, I' m just about finished. Could not make it to the store as we had a sheet of ice fall on our little town. https://cimg3.ibsrv.net/gimg/www.rx7...fa202af63.jpegI also worked on straightening the seam. Massaging things back to normal from some ill placed jack points in the past.