I don't see how sticking tint film onto the outside surface of the glass would make it porous unless you're using hydrofluoric acid in the adhesive.

Muratic acid.

This procedure that our PermaBrite provider uses actually acid "etches" the surface before applying the porcelein impregnated coating.

The real way to do it is with an acid wash and stain.

I don't think it was an acid, but when a drop fell on my skin it started to burn a little bit.

Muratic acid is a stronger alternative to vinegar, if everything else drains well, and the toilet drains well when you dump in a bucket.

Sorry for diverting, but has anyone tried a technique of using a stud finder to drill between wall studs, and then squirting (if you can squirt a powder) Boric acid into the holes?

Maybe you could do acid wash to brighten the brick a little bit.

The only thing I've ever found that works is powdered sugar mixed with boric acid (not boraxo) about 2/3 sugar to 1/3 boric acid.It's poison, so place where pets and kids can't get it.The ants carry it away, so it isn't there very long.

I heard they are tainted with sulfuric acid that can damage your plumbing...