Years ago a guy installed glass blocks where my old coal chute is. He used what looks like concrete to cement the blocks together but, between the metal of the coal chute and the glass blocks, he sprayed some foam sealer. The foam sealer expanded to the outside of the chute (and house) so he trimmed the foam sealer and covered it with a gray, smooth protective substance. That substance is breaking down and I want to know what I can use to protect the foam sealer from the elements.

No one at the stores knows how to deal with this and my voice is cracking from asking them.

Any ideas?

Thanks.