Rotary Tumbling: Fine Grit Cycle
The fine grit stage, usually 500+ fine grit, prepares your stones for the polishing stage. The shaping of your stones is finished. So now the surfaces are being prepared to take a polish. The fine grit stage can be anywhere from one to three weeks. The grit "wears out" during the tumbling process thus getting finer and finer. We recommend at least two weeks in the fine grit. The better the surface on your stones the better the polished surface. A pre-polish can also be used after the fine grit and before the polish; especially if you are tumbling quartz or other softer stones. There are Aluminum Oxide and 100 grit available. The Aluminum Oxide is best for softer stones and the 100 grit is best for agates, jaspers, and quartz. One week to ten days is good for the fine grit, and repeat for your pre-polish stage. The surfaces of your stone should look slightly shiny when ready for the polish stage.
The grit on the left is 500 and finer (fine) grit. The grit on the right is 1000 and finer grit also known as pre-polish. The numbers or "range" in the grit is determined by the number of granules per inch if they were placed end to end.
The image on the left has been tumbled with 150-220 grit. The image on the right has been polished with the 500(and finer) grit, and is ready for the polish or pre-polish stage.
The image on the left here is Aluminum Oxide a form of polish. The image on the right is of Cerium Oxide also a polish. The difference between these two will be discussed in the next Lapidary tip on the polishing stage.