Professional Jeweler Archive: The 3M Radial Bristle Disc Proficiency Advantage

August 2003

Professional Bench/Tool Tips

The 3M® Radial Bristle Disc Proficiency Advantage

The extensive selection of 3M radial bristle discs and end brushes provides a proficiency advantage

David Howard has reinvented how he semifinishes castings and performs other prefinishing techniques thanks to the growing inventory of 3M® radial bristle discs and end brushes. “They are flexible, cool-running, clean and non-loading and provide a controllable uniform finish,” he says. Here’s an overview of semifinishing a rough casting using the discs.

1. After casting this 14k yellow gold pendant, remove the sprue by sawing and filing, then remove visible defects by filing. The pendant is ready for semifinishing with the radial bristle discs.
2a. Start by using the
6-in. blue bristle disc (400 grit). The pendant won’t require much time at this stage because the wax and resulting casting are in good shape.
2b. Now use the pink bristle disc (pumice equivalent grit) on your flex shaft at the bench. When using bristle discs, the end of the brush should be all that comes in contact with the surface of the piece.
3. Next use the peach disc (6 micron grit) and then finish with the light green (1 micron grit). No cleaning is required between the steps. This photo shows the pendant’s finish after the peach bristle disc and before polishing with rouge. Because the design is rounded and has recessed areas, the bristle discs are flexible enough not to remove too much metal in one area or create flat spots and divots. The variety of grits, shapes and sizes makes semifinishing a casting quick and efficient.

Additional Product Information

4. The 3M® Radial Bristle Discs come in a variety of sizes and diameters ranging from 9/16 to 6 inches and can be mounted and used with flexible shafts or bench motors. The multiple diameters are available in a color-coded assortment of seven grits. They are used for cleaning,
5. This is a 1-in. diameter green bristle disc. The center hole on the 1-in. disc requires a mandrel with a 1/8-in. diameter screw. The green disc’s abrasiveness is equivalent to 50 grit and is one of the more aggressive in the assortment.
6. This photo features an assortment of 2-in. and 3-in. 3M radial bristle discs.
7. Shown are a few of the 6-in. discs. The center hole accepts a fitting that can be secured to a tapered mandrel. It also comes with an adapter to be secured to a 1/2-in. motor shaft.
8. The 2-, 3- and 6-in. discs require a tapered spindle mount sold separately. (A) accommodates 2- and 3-in. wheels; (B) accommodates 6-in. wheels.
9. Rio Grande supplies 2- and 3-in. discs permanently mounted on a hub in three- and six-ply widths. The three-ply typically is used in less aggressive applications, the six-ply for larger pieces requiring a more aggressive, broader approach.
10. These end brushes work well in tight, difficult-to-reach areas. They also work nicely for a spin finish on flat stock.

Howard and Henson say the bristle discs can be used with gold, silver or platinum.

3M sponsors this installment of Tool Tips. For information on 3M materials for bench jewelers or for a list of distributors, contact Rich Bohr at (602) 432-5547,

Rio Grande provided technical consultation and bristle discs for the photographs. Rio Grande supplies a full range of 3M® prefinishing and finishing products and technical help. For more information, call (800) 545-6566.

David Howard (505-889-8601), a retail manufacturing jeweler, provided technical consultation for this article.

– by Mark B. Mann

Technical Contributions by JA® certified master bench jeweler David Howard, owner of My Jeweler, Albuquerque, NM, and Curt Hensen, Product Manager from Rio Grande, Albuquerque, NM

Photographs by Mark B. Mann
©2003 Visual Communications

Copyright © 2003 by Bond Communications