All Mirka Silver-series discs feature a flexible and strong latex-impregnated paper backing. This feature is one of the reasons Silver discs can be used wet or dry. Thicker backings are typically used for coarse grades of paper, while thinner backings are used for fine grades of paper. See the specifications page for more information.
Coarse-grade discs (P80-P500) feature aluminum oxide abrasive grains, while fine-grade discs (600-1500) feature heat-treated silicon carbide abrasive grains. Each type of grain has been chosen for durability and performance. Heat-treated silicon carbide grains maintain their shape throughout the sanding cycle, so they work especially well on thin yet hard surfaces, such as ceramic clear-coat paint systems.
Resins are used to glue the abrasive grains onto the latex-impregnated paper backing. Resins are also used to coat the abrasive grains, so they will work in a specific manner. Not only do resins have to be strong, they have to have a positive effect on overall sanding performance. If the resin covers the abrasive grain to the point that it cannot efficiently remove material from the sanding surface, what good is that?
Additionally, resins have to be able to handle high operating temperatures. Otherwise, the abrasive grains will detach from the backing during rigorous use. Loose grains can wreak havoc on an otherwise properly sanded surface. Fortunately for us, Mirka really did their homework in this department. Silver discs consequently deliver long lasting, consistent performance.
The quickest way to render a sanding disc useless is to allow sanding residue to attach to the face of the sanding disc. When a sanding disc becomes clogged with paint, metal, wood, or plastic, the abrasive grains can no longer create a consistent sanding result.
To combat clogging, a specialized coating called stearate is applied to Q-Silver and Q-Silver Micro Discs. The stearate essentially fills in the void areas between the abrasive grains, and coats the abrasive grains themselves. Once an abrasive grain comes into contact with the sanding surface, it wears away, exposing the grain as it moves.
Standard Silver Discs do not feature stearate, and unless you are working with a very specialized material or coating that has an adherence issue to stearate residue, there is no benefit from its absence. We stock Q-Silver and Q-Silver Micro Discs, and are happy to order in standard Silver Discs for you by request.