So THAT is what's behind the slime in my coffee pot!

Tadchem,

I think you are on to something: I have found that spray bleach works very well in getting coffee residue out of my stainless steel coffee maker carafe. Perhaps the high ph is doing the trick!

This should motivate weekend lab workers to just mix stuff from their old shelves and not throw away any fluffy junk that results. Obviously, few have such spontaneity, given how many decades this combination went undiscovered. The graphene Nobel prize is another example of how unplayful entire generations of graduate students can be.

few have such spontaneity, given how many decades this combination went undiscovered

In this case you're rather demonstrating the lack of informations or the willingness to do a brief review at Google first. The tannic acid layers were tested long time ago as an anti-rust coatings just for protection of iron surfaces. These guys rather did a characterization of these films with modern methods. I wouldn't compare it with graphene finding.

Sounds curiously like the iron gall ink that was the standard ink used in Europe from the 5th century to the 19th century.

It was made by mixing iron(II)sulfate with tannins from oak gall immediately before writing. When you write, the ink first appears light brown. After a while it oxidizes to brownish-black iron(III) tanate.