X-Phobic is an additive that cleans all contaminents and removes Rain-X off the glass surface. Rain-X and other hydrophobic coatings block windshield repair resin from linking to the glass. If Rain-X has been shot into the break from windshield washer fluids, a car wash or has migrated into the break by windshield wiper use the repair will be adhesively compromised. X-Phobic eats the Rain-x off the glass, cleans and etches the surface for a superior bond. Add 1 drop to 4-5 drops of resin into your injector and stir with a toothpick. Then do the repair. One bottle will do 60 stone-breaks.