Hey folks, I'm doing some work restoring the gas tank and have access to the area that would be blocked by the tank. The car was previously restored, and looks like they did an epoxy layer and then some rubberized undercoating. I want to do a few bits of minor repair and follow the same approach. I've been trying to see if I can match the rubberized undercoating but I'm not quite sure what was used. I don't think it's bed liner as it's not rock hard.

I know it's a bit of a longshot, but figured I'd post a picture to see if anyone recognizes it. I thought it might have been 3m Schutz but after getting a closer look at how that lays down, I'm not sure it's that. I might pick up some Transtar 4363-F and 3m 08883 rubberized undercoating and see if one of those is close

 

Undercoat that is applied by Schutz usually has a more gloppy texture, I'm guessing that was done with rattle can undercoat. The coat on this car has the same consistent texture as yours does but has a bit more of a shine.

 

 

Thanks! Circling back as I'm finally (jeeze) getting back to this. I ended up picking up some of the SEM rubberized undercoating (the regular and low VOC) versions but neither look particularly close: they are quite glossy and don't have much texture to them.

The stuff on my car has a fairly pronounced texture, is pretty matte with a fairly grey hue (this could just be from time though) and doesn't seem to be completely dry to the touch. In the wheel arches there is dirt and such embedded in it

I wonder if that's just gonna be challenging to match with a spray can.

Edited February 9Feb 9 by hotsho111

This isn't the best picture, but here's one of the undercoating in the rear wheel arch corner. I'm not sure it's the same stuff that's used on the flat surfaces.

 

Will continue to post some updates as I continue through this as people sometimes PM about random threads. I did some test sprays on the spray can rubberized undercoating from SEM I got and while I like the finish, it's not nearly as close to the existing undercoating. SEM has instructions for a "textured" and "smooth" finish (really based on how far you spray a final light coat) and I tried both approaches.

Here's a test piece I shot next to the existing undercoating.

It doesn't come across quite so well in this picture, but the spray coating on the test piece is basically as thick as a coat of paint, where the undercoating on the car is significantly more thick. - like 1/16-1/8 of an inch in a few places.

I have a feeling this was undercoated using an undercoating gun like this https://www.amazon.com/Astro-4538-Economy-Air-Undercoat

I don't think it was 3m Schutz, and it seems to look close to 3M UnderSeal Rubberized Coating (8819) but I that might not be available in the states. I do have receipts from some of the body shops that worked on the vehicle during it's restoration, so I tried reaching out to any of them to see if they might know

Otherwise, I might try and see if I can find an undercoating and try spraying it through and undercoating gun instead of a spray can.

It might be Wurth Stone Guard.

Wurth USA

Wurth Stone Guard Video

(edit): Whoops, just noticed that what you are trying to do isn't match factory - so disregard. 

I was quite interested in this topic a while back.  I think the best replica I have seen is what was used here (starting at about 6:25):

 

Edited February 19Feb 19 by inline6

Thanks Kickstand, and I still appreciate the video inline. The shortlist of products I've found are

• 3m Body Schutz
• 3M UnderSeal Rubberized Coating (8819) - this doesn't seem to be available in the states
• Wurth's Stone Guard
• Rusfre undercoating
• Domion Sure Seal
• Transtar Undercoating (4361)
• Sem undercoating
• KBS undercoating

I'm sure there's a million more though.

Going through my records I *did* manage to find the shop that did the restoration of my Datsun (in Spokane, WA, but I don't want to put them on blast). Unfortunately the shop owner retired in 2021 so I haven't been able to reach him.

Edited February 22Feb 22 by hotsho111