Lapping is a process of polishing whereby an abrasive is rubbed between two pieces of material, one harder than the other, to produce a shiny surface on the harder material. This is accomplished because the abrasive embeds itself into the softer material, creating a perfectly flat abrasive surface to polish the harder material. Lapping is used extensively in the production of optical glass because it produces a much flatter surface than is possible with other polishing methods.
Things You'll Need
Apply the lapping compound to the surface that is to be ground. The compound should completely cover the entire surface, but does not need to be evenly applied. Placing the polisher on top of the surface will even out the compound.
Place the polishing surface on top of the lapping compound, pressing down to even out the lapping compound and flow excess compound out of between the item to be polished and the polishing surface.
Move the polisher across the surface being polished, moving gently to avoid incorrectly scouring the surface. The polisher should be allowed to use its own weight to do the work. You don't have to press down on it. Check the polished surface every five minutes to determine how much more polish is required.
Wash the lapping compound off of the polished surface using clean water. When the water runs off clear, wipe the surface with a clean cloth to dry it out.