Glass Pro Putty is an outstanding fast-setting black colored stained glass cement designed for strengthening and waterproofing leaded glass panels. It is better than regular putty and more economical than competitive cements. Also, it cleans up easily with whiting. It's a ready to use oil-based elastic compound that is easily applied. It adheres tenaciously to came and glass, expands and contracts with weather, and forms a tough surface coating while remaining permanently elastic. Apply at temperatures above 40 degrees F (4.5 degrees C).