The efficient dust removal provided by these discs helps keep the abrasive surface cleaner for better sanding.
Furthermore, they last longer than the same discs without the holes, whether or not they are used with a vacuum!
In this group of products 3M has combined its original dust-free hole pattern with the premium Purple abrasive family for both dust extraction and superior abrasive performance.
• All these discs have a stearate coating to prevent loading and provide a consistent finish
• Resin bonded for heat resistance
• Surprisingly, tests show that this original hole pattern exhibits its best dust extraction when used with one of 3M's new Clean Sanding Backup Pads, rather than the original Dust Free pads that match this hole pattern.
• Priced by the box
• Note — Among 3M's Purple "dust free" 6" disc offerings, all the discs coarser than 80 grit, as well as all 8" Purple dust free discs, are only available in this group, with the original dust free hole pattern. (That is, they are not available in the Clean Sanding format.)
Heavy on the technical side....
Purple abrasives are 3M’s best performing class of abrasives.
Both more durable and faster cutting than other discs, they provide the greatest dollar value and the highest quality in abrasive minerals available.
Faster cutting increases productivity, while long-lasting abrasive particles reduce disc consumption — so shop techs spend less time changing sandpaper and more time sanding.
Purple discs are constructed of a unique blend of premium aluminum oxides and an incredibly durable, man-made ceramic mineral, Cubitron, for longer disc life.
• 745I - light purple discs come only in 80 grit, they have an evenly distributed closed coat abrasive pattern on a heavy E-weight paper backing
• 740I - dark purple discs are very coarse, with a non-loading open coat abrasive pattern on a heavy E-weight paper backing