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Abrasives 101

ABRASIVE MATERIAL TYPES:

Aluminum Oxide (A/O) – One of the most popular abrasive materials, aluminum oxide is the industry standard for common applications. A/O is excellent for planing, stripping, roughing, and finishing on all wood types. It is also great for snagging, weld removal, and grinding of metals. High quality aluminum oxide is highly friable, meaning the tips of the abrasive grains fragment as it wears, continually providing sharp cutting surfaces, and increasing working life. Aluminum oxide abrasives are highly customizable to specific applications. 

Silicon Carbide (S/C) – Silicon carbide is popular for finish work because it delivers extremely consistent, even cutting. It is harder and sharper than aluminum oxide, so the cut rate remains the same through the entire life of the belt. It's ability to remove material without excessive heat buildup makes it perfect for sanding stabilized wood, resins, epoxy, and other heat sensitive applications. Silicon carbide is also excellent for automotive paint preparation. Other applications include marble, garnet, glass and other solid surfaces. It is typically black in color and acceptable for applications requiring waterproof materials. 

Ceramic – Considered a premium abrasive grain, it is extremely hard and sharp. Ceramic abrasives are ideal for aggressive cutting of metals and hard woods. It is so aggressive, caution must be used to prevent scorching of the working material. Ceramic is friable, continuously delivering a sharp cutting surface, increasing the already impressive longevity of the product. It is typically available in low grits, topping out at 220 grit.  

Zirconia or Alumina Zirconia (A/Z) -  Zirconia was the most aggressive and durable abrasive grain until ceramic came along. It is still an excellent choice for heavy metal grinding / polishing of metals and material removal in hardwoods. Zirconia sanding belts are less costly than ceramic and do not typically exceed 220 grit. 

Non-Woven - Non-woven abrasives are produced from a variety of materials and are typically measured in coarse, medium, and fine increments, rather than grits. Products made from non-woven materials are often used for buffing and polishing metals, deburring, cleaning, rust and grime removal. Non-woven abrasives are waterproof and durable. They are also used as an alternative to steel wool. They come in various colors.

 

ABRASIVE MATERIAL BACKINGS:

Paper –Paper backed abrasives typically include aluminum oxide and silicon carbide belts, discs, and shop rolls. Paper backing has some advantages, such as its light weight and lower cost compared to cloth backing. It also delivers even cutting for delicate processes and finer grits. However, paper alone does not provide the rugged durability of cloth or synthetic backings. Paper backing can be infused with material such as latex, to create an extra flexible, durable product that delivers consistent scratch patterns. Some industrial and professional users require paper wide belts for specific woodworking, stone, granite, plastics and metal finishing applications.

Cloth (Cotton, Polyester, Poly/Cotton Blend) Cloth is a popular backing due to its cost effectiveness and strength. Premium abrasive products typically feature cloth or other synthetic backings. Polyester is a waterproof, synthetic backing that offers superior strength and longevity. Most standard sized belts are cloth backed. 

Plastic/Film - Plastic film backing is excellent when users require an extremely uniform finish. It is popular in wet sanding due to its waterproof properties, strength, and flexibility.

Foam and Sponge - Foam and sponge backings are best for hand sanding moldings and veneers. These materials form fit contours and are an excellent choice when flexibility is required.

WEIGHT:

Coated abrasive products are categorized by the ‘weight’ (wgt) of the backing material used. This alphabetical system indicates the stiffness and thickness of the backing. Below is a list of commonly used weights:

Paper – A (Lightest) – F (Heaviest)

A & B wgt are common in low-end materials and/or finer grits. They are typically used for hand sanding applications. C & D wgt are the most popular for general use sandpaper products. E &  F wgt are most commonly used for belts and discs.

Cloth – J (Lightest), X, Y, YY (Heaviest)

For most applications, a good ratio of weight, flexibility and flatness are crucial for abrasive product performance. J wgt material is the lightest and most flexible. This is popular in light metal finishing applications. X wgt has the widest range of applications. Y wgt is typically used for heavy duty applications. Cloth materials are stiffer and used in most belt sanding applications due to their increased strength. Paper backing is used when uniform consistency is needed. Paper backed materials are used in hand sanding applications such as polishing and fine wood finishing.

Other weights (S,T,M) are seldom used, only for specificapplications and products.

JOINING:

Abrasives can be joined together to make a continuous belt in a variety of ways. Smaller pump sleeves glue the backing together while most belts use a combination of tape and glue. Different joining methods produce different results. Some industrial manufacturers require joints that are specific to their operations. Red Label belts are butt tape jointed, bi-directional belts, which means they can be run both directions flawlessly. As a manufacturer, we offer a variety of joining types for applications with specific requirements.

COATING:

Coating refers to the amount of abrasive grain applied to the backing material. In general, closed coats provide an even finish on solid materials and open coats provide better finishes on woods.

Closed Coat: Grain is applied evenly together without any voids in the coat. It delivers a longer life and finer finish. Typically used in non-woodworking applications

Open Coat: Only a portion of the backing is covered with an abrasive grain. This type of coating reduces loading in coarser grits. The backing is covered 50%-70%, allowing more room for material buildup to expel from the grain.

Semi-Open or Semi-Closed: In between closed and open coat.

OTHER TERMS:

Stearated / Non-Stearated - Stearate is a chemical application to the surface of an abrasive product that reduces the adherence ability of materials. The process of sanding creates heat. Heat build up can be quite significant and can melt the surfaces and particles being sanded. Stearate reduces heat and buildup by reducing friction.

Loading: Loading is a condition characterized by the spaces between abrasive grains getting filled with small particles of the material being sanded, reducing the effectiveness of the abrasive product.

Waterproof– Certain finishing applications generate massive amounts of heat. Water is sometimes used as a coolant, and requires synthetic waterproof backings. Other applications require the use of water-based compounds when waterproof materials are required.

Grit - Grit refers to the cutting ability of a material. It is measured as the amount of abrasive material per square inch. The United States and Europe have different grading scales. As a large percentage of raw abrasive materials are imported or produced in facilities owned by European companies, it is important to decipher the difference between these scales. The US uses the CAMI (Coated Abrasive Manufacturers Institute - now Unified Abrasives Manufacturers Association) standard while Europe uses the FEPA (Federation of European Producers of Abrasives). European scaling is designated with a 'P', followed by the grit number.