don't use any additives, it could be bad... if anything, take your lighter, and hold the screen with pliars or something and burn the shit out of it... continue burning it til the screen is clean.. you will once in awhile have to rub at it to rub the ashy-burn crap off... after a few good 20-30 second burnings you should be good to go, it should burn off any impurities... and is atleast safer then soaking something in clr, or other harsh chemicals you're gonna be smoking out of (no offense, it was a good guess)