Tar in trunk on my 37, Amazing preservation

So I picked up this 1937 Plymouth 2 door business coupe and I'm amazed by how rust free it is. I cleaned the trunk out today and it was covered in a asphalt tar like product. It was lifting off in areas so I decided to remove some of it and I was amazed how preserved the metal was. zero rust, no pitting and the primer looks almost new. Was this tar stock? Has anybody ever seen anything like this before?

After

Looks great. Take a propane torch & heat the stuff a little & it'll come off like butter. (bench test some of it first & make sure it doesn't splode or burst into flames though on the car!!!)

Cool looking ride.

My 48 & 49 Plymouths had similar tar under coating. My 31 didn't.

my 38 had that exact same stuff not only in the trunk, but also behind the front seat and up the riser to where the trunk floor came through into the passenger compartment. that area was also covered. since it was a business coupe, i'm guessing it was used because it was way more "wearable" than the rubber floor mats of the day, and items could be slid in and out without harming the surface, yet keep said items from sliding back and forth while going down the road.

Probably asbestos...

Keeps the moonshine from leaking out.

Pretty cool. Thanks for posting it.

So, does that look like it was applied by the factory, or would it have been something an owner did after the fact?

I suppose it might be difficult to know with a car that has 80 years of history behind it!

Everything had asbestos back then

I'm just guessing but I think it was factory applied, the primer underneath is too nice to have been applied later

It could also have been a dealer-installed aftersale item. Probably helped with reducing noise in the trunk.

Interesting. Can't recall seeing that before but then most 30s-40s cars I've seen had a rubber mat in the trunk that I wouldn't have looked under.

It was very thick in some places, almost 1/4 inch thick

I don't ever remember seeing much of any original floor pans remaining, on any of the 30s or 40s Mopars I've had, much less what might have been covering them.

There were a few places where I've encountered some type of undercoating that looked a lot like that stuff. I suspected it was originally factory installed. It was some good stuff! I've seen clean shinny steel under it, next to rotted away sheet metal that was not protected by the undercoating. If only the entire floor would have been covered, the sheet metal might have still been good. Gene

I'd be worried it would catch fire and not being able to put it out.

You have probably finished the tar removal but this MIGHT (? ) help someone else maybe, well maybe not , well not at all. The heck with it I'm not posting (just kidding).

My '56 Canadian Dodge 2 door wagon (Plodge) has a similar tar on the floor boards under the seats (lower right in pix) and I had a air powered gasket scarper air chisel that I have not used much that worked very well.