Face polishing granite is the process of polishing the top of the stone and should be avoided at all cost since the process is very time-consuming. You should only attempt face polishing if the top is scratched. If the top is small enough, it may not be worth the time and effort it takes to polish and a new piece may be necessary. However, if you must face polish, the following are the procedures:
- Electric or air polisher
- Complete set of Alpha Turbo Wheels (100-200-500-1,000-2,000-3,000-buff)
- Turbo wheel adapter
- Clean the polishing area to remove any grit, dirt or trash.
- Make sure the stone is placed flat and solid. There should be no hollow spots underneath.
- Secure the stone as necessary to avoid movement during polishing.
- Clean the face of the stone to remove any grit, dirt or trash.
- Check the product’s MSDS (material safety data sheet) to determine the PPE (personal protective equipment) necessary for this task. Be sure to put on your PPE before beginning any grinding, honing or polishing.
- Examine the stone to determine the finest grit capable of removing the deepest scratch, unevenness from sticking, or adhesive from fill and sticking. Typically, you will need to start with at least a 200-grit abrasive.
- Clean your abrasive to remove any dirt or trash.
- Attach your abrasive to the backer pad. For face polishing we recommend using a rigid bond abrasive such as the Alpha Turbo Wheels and rigid backer pad to help eliminate an uneven surface.
- Spray the stone with water from your right-angle grinder/polisher to wet the stone and wash out the tool before polishing.
- Adjust the water pressure. Use only enough water to flush away the slurry…grinding will require more water than honing and polishing. If you do not use enough water, then your abrasives will not cut as well because they will be clogged with slurry or they may burn the stone. If you use too much water, your abrasives will hydroplane, float on the water instead of the stone. This normally occurs with finer abrasives.
- Check and adjust the speed for the task you are performing. Be sure not to exceed the recommended rpm for the abrasive you are using.
- Place the abrasive flat on the stone and turn the machine on. Keep the abrasive flat at all times to avoid gouging or creating a dip in the surface.
- Use a slow pattern that evenly covers the surface of the stone. If you need to change directions, do it slowly and evenly to keep the abrasive from tilting and gouging or creating a dip in the stone. If you are spot polishing (polishing one small area, not the entire surface), then cover a gradually larger area with the next finer grit abrasive to feather it out. Do not allow the abrasive (backer pad) to extend beyond the stone during the initial grinding and allow it to extend with the finer grits. Do not allow the backer pad to extend more than one-third beyond the edge of the stone—especially if using three 3-in. discs on a 7-in. backer pad!
- Once you are finished, gently lift the abrasive off of the stone as you turn the power off and wash the stone before turning the water off. I recommend varying your starting and stopping locations and always keeping the abrasive moving while the tool is on to avoid any low spots in the stone.
- Remove the water with a squeegee and allow the stone to dry.
- Inspect the stone for an even abrasive pattern. If the pattern is uneven, scratches remain, etc., repeat steps 7 to 15 with the same abrasive or a coarser one if necessary.
- Repeat steps 7 to 16 with the next finer grit abrasive until you are ready for the final polish. You can polish the stone in most cases without the use of the final polishing procedures. When you inspect the stone and see a slightly reflective finish with no visible abrasive pattern, then you can go straight to the final polishing procedure. Some people insist on going through all of the abrasives first, which is not necessary on all stones. I only recommend skipping abrasives on soft stones. Skipping abrasives can sometimes take more time and increase the amount of wear on some of your abrasives.
Final Polishing Of Granite With Powders
- Electric or air polisher
- Hard back drive pad (3 to 4 in.)
- Felt polishing pad
- Granite polishing powder (dark and light)
- Check the product’s MSDS to determine the PPE necessary for this task. Be sure to put on your PPE before beginning any grinding, honing or polishing.
- Equip a drive pad to your polisher and attach a felt pad or buff wheel. Clean your pad to remove any grit, dirt or trash.
- Spray the stone and the pad with water. Leave just enough water on the stone for the powder to form a slurry.
- Adjust the machine to around 1,000 rpm.
- Sprinkle the polishing powder over the surface of the stone. Use the black powder for dark granites and the white powder for light granites.
- With the machine off, use the pad to spread the slurry over the stone.
- Without water, start the machine.
- Add water and work the slurry until it is dry and removed from the face of the stone, but do not allow the stone to get so hot that it breaks.
- Spray off the stone well, then use a squeegee to remove the water and allow it to dry.
- Inspect the stone to determine if you have achieved the desired polish. If not, repeat steps 4 to 9.
About the author:
Frederick M. Hueston runs the National Training Center for Stone & Masonry Trades, Asheville, NC 28806; www.ntc-stone.com; and can be reached at Fhueston@aol.com.