The Stovebolt Site Forums The Shop Area Paint and Body Shop toe pan black strips

I am cleaning up a '53 cab to replace the wrecked one on the Blue Funk.

On the toe pan, at the place where the right fender and left where the parking brake bracket attach, I removed strips of some sort of black substance similar to asphalt.

For future reference when I put things back together again, I need to know: What are these strips?

Thanks.