Open Coat Construction Provides Aggressive Cut and Reduced Loading
3M designed these discs with an anti-load coating and open coat surface to increase efficiency and product life by minimizing loading. The abrasive is resin-bonded and supports disc flexibility without sacrificing durability and reliable performance under high heat and pressure. To compliment the effective abrasive action, the polyester film backing flexes to help achieve a consistent finish over contours and offers greater tear-resistance than comparable paper products, making it ideal for high-production environments. And the pressure sensitive adhesive (PSA) provides easy attachment, holds the disc securely in place during use, and removes cleanly from the backup pad (sold separately). Designed for use with orbital and random orbital sanders, this disc comes in a range of micron grades for complete multi-step sanding and finishing.
  Precision, Micron-Graded Aluminum Oxide Abrasive Offers a Fast Cut, Long Life, and Uniform Finish
The 3M™ Microfinishing PSA Film Disc 366L features precision, micron-graded aluminum oxide, which is a popular choice among industrial professionals because of its fast cut-rate and long life. This mineral makes a tough, durable abrasive that self-fractures to expose fresh cutting edges, whereas traditional natural abrasives dull more quickly. Due to its fast cut-rate, hardness, and strength, it is widely used in grinding applications in addition to sanding and finishing applications. Aluminum oxide is suitable for a wide variety of materials in both woodworking and metalworking, including ferrous alloys.

Sanding discs cut better and last longer when dust isn't clogging the cutting surface of the abrasives. Open coat construction means the abrasive grains are placed with space between them to help evacuate sawdust and other sanding debris and avoid clogging the cutting edge of the grains. The load-resistant coating also allows the disc to continue cutting even when sanding softwoods, paints, and other materials that would, otherwise, clog the disc and hinder sanding ability. Additionally, the open coat feature provides a more aggressive cut than a comparable closed coat abrasive of the same grade. All of this adds up to increased productivity and reduced material consumption.

3M™ sanding discs come in a variety of forms to fit various power tools and