8 Expert Tips on How to Polish Rocks
1. Grind wet. Always grind wet to protect your lungs from breathing in the dust from stone polishing. The dust from some stones, such as malachite, is quite toxic. In addition, wet grinding eliminates damage to expensive diamond wheels and stone-polishing tools.
2. Judge dry. Although we always grind wet, we recommend that you always dry the stone completely before judging its surface. Water on the stone surface will only hide scratches and give a false reading.
3. Use the whole wheel. Use the entire width of the grinding wheel, not just the centre. This will ensure a longer life and better performance for your diamond wheel.
3. Use the whole wheel. Use the entire width of the grinding wheel, not just the centre. This will ensure a longer life and better performance for your diamond wheel.
4. Skip no grit. Work sequentially from the coarsest to the finest grit. Don’t be tempted to take a short cut by skipping a grit in order to save a little time. The progression through finer and finer grits is necessary to remove the scratches left by the previous grit. The goal is to have the scratches become finer with each grit size until they can no longer be seen. Our experience has been that if you skip a grit, the final polish will show big scratches.
You will wonder where those scratches just came from! The truth is that they were there all the time, but you just didn’t sand them out when you were supposed to. If you skip a grit and find deep scratches, you’ll have to go back three or four grits to remove them. It’s always faster to do it right the first time than to try to take shortcuts and risk damaging the stone you’re working on.
5. Polish slow. Polishing is the final step. There are a myriad of polish and stone-polishing pad combinations; our preference is charging a soft leather pad with a thin paste of polishing compound and water. The actual polishing occurs as the pad starts to dry and the stone starts to pull against the surface. We keep the speed of the pad low to eliminate any heat buildup.
6. Keep it clean. Remember, “Cleanliness is next to Godliness” is especially important when it comes to lapidary work. To prevent cross-contamination from coarse grits, we are careful to rinse the stone and our hands at every grit change during stone polishing. We also thoroughly clean our machines after each grinding session to prevent contamination when moving through grit levels.
7. Believe what you see. Your eyes are your most important tools when it comes to stone polishing. They are your feedback loop. If your eyes tell you that something is not quite right about the surface, believe them. Stop! Figure out what the problem is before continuing, and think through the steps you’ll take to remedy it before you begin.
8. Grind a little and look a lot. This is the mantra of the successful lapidary. Taking your time and being very observant during the polishing process is essential to secure the results you want.