Tin Cure Silicone Rubber 20 Shore A 100:2 RTV-2 Liquid Silicone for Cement Wall Tile Molds This 20 Shore A tin cure (condensation-cure) RTV-2 liquid silicone rubber is a two-component, industrial-grade mold-making silicone supplied as HN-620 in the HN-6XX series. Mixed at a simple 100:2 ratio by weight and cured at room temperature, it delivers a soft yet tough elastomer with no oil bleed, good tear resistance, fine pattern replication and multiple demolding cycles — a