Long-lasting Durability Handled with care, an agate burnisher can endure a lifetime of use. However, they are relatively delicate and prone to chipping if handled roughly Maintenance and Care To maintain their smoothness and condition, agate burnishers require proper care. They can be smoothed using the fesh side of a piece of leather coated with whiting. Alternatively, a zinc-lined board coated with a mixture of flour or emery and machine oil can be used for rougher surfaces.