C.R. LAURENCE WCS1 CRL Water Clear Silicone Sealant - 10.3 Fluid Ounce Cartridge. CRL Water Clear Silicone Sealant is an optically clear acetic cure, 100% silicone sealant that cures in the presence of atmospheric moisture to produce a durable and flexible silicone rubber. Its unique weatherability enables it to retain its original properties, even after years of exposure.. Part Numbers Variations: WCS1