Translucent and opaque colors are produced by adding pigments and opacifying agents. Cellulose fibers improve strength and dimensional stability and reduce light transmission. Moldings made from amino compounds are hard, rigid, abrasion resistant, and have high resistance to deformation under load. They do not impart taste or odor to foods, and they have excellent electrical insulation characteristics. Urea and some melamine molding compounds have flammability ratings of 94V-0.
Melamines containing alpha cellulose, mineral, or glass fibers have the greatest flame resistance.
These materials can be used for appliance parts classified by UL as indirect supports of current-carrying parts. Melamines and ureas are not resistant to strong oxidizing acids or strong alkalies, but they can be used safely with conventional household chemicals such as naphtha and detergents. They are unaffected by organic solvents such as acetone, carbon tetrachloride, ethyl alcohol, heptane, and isopropyl alcohol. Dimensional stability is good, but moldings do swell and shrink slightly in varying moisture conditions. Baking of molded parts accelerates postmold shrinkage and improves dimensional stability, dielectric strength, and dissipation factor.