Bondo All-Purpose Blue Cream Hardener mixes with two-part fillers, putties and glazes to create high-quality, long-lasting repairs. The white cream hardener is ideal for situations in which a neutral color is preferred. The white color allows for keeping the mixture the natural color of the filler/glaze or adding a customized tint if necessary. When filler and hardener are mixed, a chemical reaction occurs to create a mixture that will deliver a strong, lasting repair. The hardener is smooth and easy to mix with fillers, putties and glazes.