How Do I Clean Black Mold in Shower Silicone? Fill spray bottle 2/3 full of white vinegar and add 2 tsp. of baking soda. Allow the fizzing to die down before installing the sprayer top. Spray the shower silicone and mold and allow the mixture to set for about an hour. This will kill the mold spores and keep them from continuing to grow and spread. Use an old toothbrush. Scrub all of the silicone and rinse it with very hot water.