Quick view Crystal Poylester Knife Grade Adhesive with Water Clear Hardener Tenax $26.46 TENAX CRYSTAL KNIFE GRADE WATER CLEAR 1 LITER Crystal knife is a high quality extra clear polyester mastic used to vertically or horizontally: Repair Rebuild Bond Fill Crystal is very smooth in consistency, and will cure shiny, is very polishable and... Out of stock! Please check back soon, or contact us to backorder.