Just read the label. Most of them will say somewhere "anti-mildew" or something to that effect and you don't want that. Just the pure 100% silicone. The brand I have is GE Silicone II W/D supreme. Look for the clear one because some come in different colors. If you're unsure ask whoever works in that department for silicone with no chemical additives in it and they should be able to point you in the right direction.