Basic Information on Prepolishing and Polishing .
LAPS for PREPOLISHING:
1200 and 1500 Grit Bonded Diamond Laps: These grits are used as a prepolish for most stones. However, the Crystalite 1200 Solid Steel lap cuts too coarsely to provide a decent prepolish. If you prefer Solid Steel laps, we suggest the 3000 Solid Steel as a prepolishing lap.
600 Nubond Lap: Nubond laps are made with a different technique than the more common plated laps. The result is a lap that cuts like a plated lap that is much finer. Once broken in, the 600 Nubond lap cuts more like a 1500 grit lap. It provides an excellent prepolish for garnet, peridot, feldspar, opal and tourmaline.
1200 Nubond Lap: Nubond laps are made with a different technique than the more common plated laps. The result is a lap that cuts like a plated lap that is much finer. Once broken in, the 1200 Nubond lap cuts more like a 4000 grit lap. It provides the best prepolish for quartz and beryl.
Prepolish Laps for use with Diamond Powder, Paste or Spray: A widely used lap for prepolish grits is Copper. Bronze is another good choice as it is harder than copper and provides flatter facets on hard stones such as corundum. BATT, Zinc and Ceramic are also good choices. If using a ceramic lap for prepolishing, keep in mind that finer grits will produce less troublesome results.
Diamond Prepolish Grits: Corundum often takes on a pitted orange peel surface when ground with a bonded lap finer than 600 grit. Therefore, when cutting corundum, loose diamond must be used for the finer grits. Loose grit can be in the form of powder, spray, or compound. If powder or compound is used, an extender fluid, such as Raytech Extender Fluid, or Crystalube should be used as a lubricant. Most people use 3000 or 8000 grit for prepolishing corundum.LAPS for POLISHING:
Master Lap: Master laps are blank aluminum laps. They are used as a base to support thinner laps like Dyna Discs and Ultralaps, that are too thin to use by themselves.
Ultralaps: Ultralaps are thin sheets that have a polishing agent on one side. They are not messy like other polishing methods, are inexpensive and easy to use. Therefore, we suggest beginners start off using Ultralaps for polishing. We have found the Spectra Ultralaps to be the best type of Ultralap for polishing quartz. Aluminum oxide "A" Ultralaps will polish garnet, as well as most tourmaline and peridot. Ultralaps are also available in Chrome Oxide, Tin Oxide, Cerium Oxide, Aluminum Oxide type "B", and Diamond in various grits.
Polishing Laps for use with Diamond Powder, Paste or Spray: Professional sapphire cutters tend to prefer brass or zinc laps for polishing. However, BATT laps tend to be more forgiving and still offer excellent results. The flattest facets are produced with Ceramic laps, but they tend to be more finicky than other laps. The Redwing BATT lap provides the best of both worlds with a copper band on the outside of the lap for the prepolish grit and BATT on the inside for polishing.
Diamond Polish Grits: Corundum is usually polished to 14,000 grit by overseas cutters. However, it will take a much better polish with finer grit. Standard grits for BATT, brass and zinc are 50,00 and 100,000. The finer 100,000 grit diamond will produce a superb polish, but takes a bit longer. We recommend 100,000 or 200,000 diamond spray for polishing corundum on a ceramic lap.
Tin Lap: Tin laps are very forgiving laps. They are excellent for use with oxide polish powders such as cerium, aluminum and super blue. Tin laps will also provide a good polish with 14,000 diamond.
Phenolic Lap: Phenolic laps can be used with diamond or oxide polishes. They tend to generate too much heat when polishing corundum (ruby and sapphire).
Fast and Last Laps: These laps are a hybrid lap that has some of the benefits and drawbacks of phenolic and metal laps.OXIDE POLISHING POWDERS:
Cerium Oxide Use with tin lap. The 99% is best for faceting. Best polish for quartz (amethyst, citrine, oro verde, etc.). Also polishes feldspar (bytownite, orthoclase, etc.) and beryl (aquamarine, morganite, heliodor, etc.).
Aluminum Oxide "A" Use with tin lap. Good polish for tourmaline garnet, peridot and beryl. Can also be used to polish spinel and topaz, but is a bit slow.
Aluminum Oxide "B" Use with tin or wax lap. Good for polishing soft and brittle stones, such as calcite.
Super Blue Use with tin lap. Great polish for harder stones such as cubic zirconium and chrysoberyl.
Chrome Oxide Use with tin lap. Chrome oxide is very messy to use and will stain anything it touches. However, it will polish tourmalines that won't polish with anything else. (We suggest using chrome oxide Ultralaps, because they aren't messy.