Basic Rock TUMBLING Instructions
· Use silicone carbide grit until stones are perfect and then use polishes for a hard shine. Grit comes in 46/70 extra coarse, 60/90 coarse, 150/220 medium, and 400 fine (pre-polish). The extra coarse grit is for a stone that needs extra grinding such as a crust around agates or very pitted stones. Most people won’t ever need it.
· A wide selection of polishes is available. Economy is a crystalline quartz polish and will shine agates, petrified wood, jaspers, etc. Aluminum oxide is for hard to polish stones. Cerium oxide is for glass or obsidian and will work beautifully on standard agates, jaspers, petrified wood. M-5 is especially good for jade and turquoise. Chrome oxide is for jade, malachite, peridot, rhodonite, or lapis lazuli. Sapphire powder is the same as Linde A, an A quality, 99.9% pure, 0.3 micron size, aluminum oxide.
· Plastic pellets are used as filler. They are not necessary, but available if you don’t have enough rocks to fill the barrel. Pellets float, so always add before the water. Pellets can be reused but only with the grit they ran with first so wash in a strainer, dry, and bag with a label of the grit they ran with. Pellets are also used as cushioning for soft stones such as sodalite and obsidian.
· Group your tumbles by hardness: petrified wood, agate, jasper can run together. Sodalite, obsidian, glass can run together. Check the Mohs hardness scale if in doubt.
· Never pour the tumbling liquid down your drain. Always empty outside.
· For large scale tumbling it is helpful to use a large, 12 lb tumbler for grit 1 stage and small 1 ½ or 3 lb barrels for other stages. It is also helpful to have separate barrels per stage as it cuts down on chance of contamination from other grits. For small scale tumbling one barrel is just fine; just be sure to clean thoroughly so the next stage is not contaminated by the previous stage.
· You can always count on losing a minimum of 30% of the original mass.
Contrary to what you will read on many other websites offering tumbling tips, silicone carbide does not go "dead." It does not "round" down and "stop working." Let's give them the benefit of the doubt and assume they are merely misinformed and are not trying to just get you to purchase more grit. As silicone carbide breaks down it continuously breaks to another sharp edge. Coarse won’t stay coarse, but it breaks to medium and then to fine and to finer, so it is definitely always working and it never rounds. You need to add more coarse periodically until the roughest rocks are perfect, but the smoother surfaces are being working by the finer grit at the same time. That’s why you do not dump out the old when you add more 60/90. If you don’t believe me look up the properties of silicone carbide or better yet look at it under a microscope and you’ll see I am right. In fact, I know people who use 60/90 only. They keep adding it until their rocks are without rough edges and then they just let the tumblers run and run and run. The grit continues to break down into finer product and eventually they pull the rocks out and go straight to pre-polish and then final polish. It takes longer, but it can be done. Personally, I prefer to use 60/90 until the stones are perfect and then use the other sizes just for a week or two because I get impatient.
46/70 extra-coarse
See instructions for 60/90. Add a 46/70 step until you feel you can move on to the 60/90 step – you will want all crust to be removed from your agates, stromatolite, agatized coral, blue forest wood – whatever it is that has a crust to be removed.
60/90 coarse
1. Fill barrel ¾ full of rocks. Add 1 tablespoon grit per pound of rocks, add water just until you can see the water. Add ½ tsp baking soda for small barrels, 1 tsp for larger barrels. Run for two weeks. Too much water will not allow the rocks to beat against each other as they should, so remember: just until you can see it through the rocks.
2. Depending on the original condition of the stones you are tumbling, the first process could take anywhere from two (for rounded river or beach stones) to six or seven weeks (for rough broken rock). After two weeks, check your stones. Pull out any that are perfect. Add more stones to keep the level at ¾ full. If you don’t have more stones, add plastic pellets for filler. You may need to remove some of the liquid. Add another tablespoon of 60/90 grit per pound of rocks. (don’t dump out the old liquid, it will continue to work, just more gently Depending on the roughness of the stones, check again in two weeks.
3. Repeat this process until you have a barrel full of perfect stones.
4. Clean all parts thoroughly – the stones, the barrel and parts, wash, dry, and store pellets to use again. Don’t forget to mark the bag with 60/90! Pellets used in one size of grit cannot be used in another size, no matter how well they are cleaned.
150/220 medium
Now the perfect stones need to begin conditioning, so they can take a shine.
1. After cleaning barrel and stones thoroughly, fill barrel ¾ full of stones and add water till you can see it. Add ½ tsp baking soda and 1 tablespoon grit per pound of stones and run for one or two weeks.
2. Clean barrel and stones thoroughly to prepare for the next grit.
400 fine / pre-polish
1. Do as above only with size 400. Run a week. Two weeks is fine also, as long as your stones aren’t too thin. If they are thin, use something to cushion them such as plastic pellets or ground corn cob. I know people in Oregon, lumber country, who use sawdust.
2. After cleaning thoroughly, add water to half way and add a quarter cup of ivory soap flakes. Run three days. Rinse thoroughly. A customer just old me that ivory soap flakes are no longer made. Try a level tablespoon of dawn dishwashing liquid per five pounds of rock and I'll keep my eye out for an ivory replacement and update this at that time.
Polish
1. Run for a week with Economy polish for a basic shine. Use a tablespoon per pound of rock and a half barrel of water. Check after an hour or so and make sure there’s enough water. After a week, test a stone by rinsing clean and allowing to dry. There should be some shine. If not, add more polish and run a few more days. Sometimes this is all the shine you will need. If you want a harder, glossier shine, go to the next step.
2. After cleaning thoroughly, add a teaspoon of your final polish choice and a half teaspoon of dawn dishwashing liquid per pound of rock to the barrel along with a half barrel of water (or the level you ended up using in Polish step 1). Check after a week. You may need to run for two weeks. When process is completed and you're happy with the final product, run for a few days with water and ivory soap flakes (dawn dishwashing liquid - see above) to remove all residue that may still be on the stones.
NEVER ADD SUGAR, NO MATTER WHO TELLS YOU IT'S A GOOD IDEA. IT'S NOT.
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