I was about to go get some dry ice to work on clearing old sound deading but I found this under the carpet. This isn't factory correct? As long as I don't find rust on the underside side I think I'll leave it. Looks too hard to remove fully. Or suggestions are welcome.

That is NOT factory. It looks painted or perhaps sprayed on...and appears thick in some locations. Very difficult to tell what it may be from the picture so this is a big huge wild guess...I'd say it is rust inhibitor of some sort (think POR15, Rustoleum, etc.) and if that is the case you no doubt have rust under it.

11 minutes ago, texasz said:

That is NOT factory. It looks painted or perhaps sprayed on...and appears thick in some locations. Very difficult to tell what it may be from the picture so this is a big huge wild guess...I'd say it is rust inhibitor of some sort (think POR15, Rustoleum, etc.) and if that is the case you no doubt have rust under it.

It does feel like a thick rubbery substance that looks to be brushed on. the passanger side has this as well and is most certainly does have rust to the point i will be replacing the floor pan. Might be doing both sides it looks like.

It looks like roof cement. 😁

I would use alcohol or lacquer thinner on a rag and wipe it to see if it stains the rag black. POR-15 shouldn't wipe off.