I'm too lazy to look for it right now, but NFPA (I think) has directions for a fireproofing solution; it uses borax and boric acid. I *suspect* they use both in order to make a buffer solution (chemical term, not important here) that keeps the pH at the right level so the sprayed material doesn't degrade as fast. Borax or boric acid alone should do the trick. Borax is usually much easier to find, and cheaper, than boric acid. Check in the section of laundry detergents. Make a saturated solution and either soak or spray the tp/paper towels.
Most "flameproof" wadding will in fact burn when exposed to a flame. The term means that it's self-extinguishing. Homemade wadding that continues to smolder, with visible sparks, isn't flameproofed enough.
Best -- Terry