120 Grit Stearate, 5 in. 8 Hole Hook & Loop Sanding Disc - Qty:5

Specifications:

• 120 Grit
• Aluminum Oxide
• Zinc Stearate
• Resin to Resin bonded
• C-weight paper
• Tear-resistant backing
• Non-Loading
• Hook & Loop backing
• Pack of 5

Aluminum Oxide (AO)

AO is formed by combining bauxite and other materials by firing them in an electric furnace. The resultant mass is then crushed, and the pieces sifted through successively finer screens to assign a grit size (CAMI grading). When crushed, the resulting pieces are naturally pyramidal in shape. Due to the shape and the strength of the materials used in its making, AO is a very durable grain. The grain is worn down during use, sanding finer the longer it's used.

AO is very tough and durable, as stated above, and is used on bare wood, most metals (especially the steels), leather and a wide variety of other materials. It is a great general purposes grain and probably the most, common grain seen today.

Silicon Carbide (SC)

SC is made by combining pure white silica sand and coke, a by-product of coal production. Again, these materials are combined by melting in an electric furnace, crushing the results and sifting the particles through screens to get grit grading. SC grains are shaped like icicles with extremely sharp points and narrow grain bodies. It is second only to diamond in hardness; however, it is very brittle due to the narrow grain body. Therefore, when pressure is applied to the tip of this grain it fractures. This characteristic is referred to as "friability". The benefit of friability is that a sharp edge is always against your workpiece providing extremely consistent finishing ability. Because of the lack of grain body strength, which allows this grain to fracture with hand pressure only, the life as compared to AO or the other grains is less. Therefore, when you see SC it's normally in finishing type operations where the pressure required for working is lower than it would be in removal grits. Examples of materials normally sanded or ground with SC would include glass, plastic, rubber, paint varnish, lacquer & sealers. It may occasionally be seen in sanding on extremely soft woods like Ponderosa Pine, but we would recommend open coat AO instead as the life would be much better.

Paper

Paper backings are available in different weight or thicknesses using the designations A (the lightest wt.) thru F (the heaviest weight). Light weight papers A-C are commonly used for power sanding with sheets or discs or for hand sanding. The heavier weights (D, E & F) may be seen in sheets or discs for power sanding or in the case of the E & F weights for belts. Only the E & F weight products are considered heavy enough to be belt materials. Some parameters that need to be met before considering a paper belt are:

1. Work must be dry. The waterproof papers we have are all A/C weights and therefore unsuitable for belts.
2. Work must be flat. Paper will not follow a contour easily and is more likely to crease, kink or tear on contoured work than cloth.
3. Work should be limited to grits 80 and finer. If you ran coarse grit belts (24-60) in paper, the backing would wear out before the grain was fully utilized. Paper is extremely well-suited for belts in grits 150 finer where it will result in a finer finish per grit than cloth and will cost less.
4. Belts should be at least 6-8 in. in width and over 150 in. long. Short belts like portable belts, belts for edge sanders, back stands or dynafile machines are usually short and narrow and therefore have less cool down time in operation. Heat is the enemy of any abrasive. These shorter belts do not provide time for the heat built up during sanding to dissipate in use and while they may at first glance appear to be less expensive, they are in fact costlier in number of belts per piece worked and downtime for belt change.