BEST PRACTICES OF POLISHING STONE WITH DIAMONDS: HANDPADS

Posted by Wednesday, November 21st, 2012 @ 1:11 pm

handpad-

Diamond handpads come in a variety of shapes, but the rectangular 2 1/4” x 4” format is by far the most popular version since it fits so easily in the palm of the hand. The handpad consists of a diamond section (small islands of diamonds on a flexible layer that permit a certain amount of flexibility) glued onto a foam support. The diamond islands are available in two basic forms:

  • Electroplated: grits range from coarse grit sizes such as #30 to fine sizes such as #1200. The most popular grit sizes for marble being #70, #220, and #400.
  • Resin bond: grit ranging in size from #600 through #3500.

Resin bond products have no scratching ability of their own other than the diamond itself. The resin base only holds the diamonds in place, making them ideal for polishing applications. The diamonds produce successively finer scratch patterns until the patterns become so small that to the human eye, the surface appears polished. As every fabricator knows, nothing is more frustrating than to finish a job and then notice scratches still present on the surface. Resin bonds are generally less “aggressive” than electroplated metal bonds. They are more forgiving and therefore do not leave large, undesirable scratches.

Sample Applications

For a typical job that calls for polishing a rough cut granite edge, try this procedure: in succession, use the electroplated #70, #120, #220, and #400 grits followed by the resin bond #600, #800, #1800, and #3500 sizes. This sequence will produce a glossy finish on almost any stone. Note that when working with marble or granite, an additional buffing sequence will bring out the full gloss of the stone.

For special applications, very fine grit diamond hand pads (8000 and smaller) or very coarse grit pads are available. For grits finer than #400, the most economical encapsulation method is resin bond because, as I mentioned above, they’re more forgiving than electroplated metal bond.

Important Considerations for Custom Handpads

Manufacturers can deliver a custom solution for every stone-cutting preference and need. When diamond handpads are tailored for each aspect of a job, manufacturers pay close attention to these important considerations:

  • Rigidity – important to maintain a flat, mirror like surface on products such as counter or table tops. Hand pads used for these surfaces are generally made with foam handles and offer the best characteristics of an all-around tool.
  • Flexibility – key to those who polish rounded surfaces such as bullnoses or ogee shapes. Diamond handpad material is available from manufacturers and can be cut into strips of any size. These strips can be fastened with hook-and-loop backing to specially shaped forms which mirror the shape of the finished edge.
  • Ruggedness – essential for heavy-material removal, such as tile edging and sizing, or even rough work on hard stones. Although still foam-mounted, custom handpads can be made on very rigid substrates with much larger diamond islands, allowing them to withstand the greater pressure.

Water is Essential to Diamond Hand Pads

For a better finish and to extend the life of the handpad, be sure to use water while polishing. Although some work can be done dry, water offers important benefits. For example, because resin bond diamond handpads are particularly intolerant of heat, water is an essential accompaniment. The water not only rinses away the cuttings (dirty water) from the stone’s surface, it also cools the diamonds and prevents the resin base from overheating.

The Power of Orbital Pads

Any time hand pads are the best tool for the job, orbital pads are the only power alternative to consider. Orbital pads are mechanically powered, and therefore offer relief from excessive arm muscle fatigue. The power tool to which they are attached should have a “jitterbug” or vibratory type of motion. This is important because if more work is done with one grit versus another (because the arm gets tired), the finished stone will not display an even degree of reflectivity and could translate to poor workmanship. Orbital pads are larger than hand pads and are available in the same grit sizes. They are also available in a wide variety of dimensions to match the power tools being used.

Don’t Work Too Hard

There’s no question a shop can experience solid benefits from the proper use of diamond hand pads. The fabricator should be able to profit by:

  • Saving time
  • Achieving consistent finishes
  • Increasing productivity
  • Reducing costs

The single most important thing to remember when using diamond hand pads – let the diamonds do the work.  In other words, don’t treat a diamond hand pad like one made of silicon carbide. Forcing the hand pad to work harder than necessary will only decrease its useful life.

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