Tips on tumbling obsidian using Vibra-Dry+ was sent in by Gary Olson. Thank you Gary for your article on a lapidary tip! Obsidian has been a favorite stone to work for Gary Olson, Powell, WY. Gary has been blind since birth and working stones is a longer process for him than other sighted persons to complete. Gary has done a terrific job with cabochons but he had been wanting to try tumbling obsidian and see how it worked. We think he did a terrific job! Starting in February of this year, Gary was sending short notes on his progress: "The Vibra-Dry+ worked great on obsidian. I used both the 25,000 and 50,000 Vibra-Dry+. I am still working out the process in terms of how long to run the tumbler with each compound. Don Depew of Diamond Pacific Tool Corp. (supplier of Vibra-Dry+) said that for one pound of Vibra-Dry, it only takes four or five drops of the extender to lubricate the V.D. again. The way you tell when you need to use the extender is when there is dust on the lid when you open the tumbler. You do not need to use any plastic pellets because the V.D. will act as a cushioning agent. The steel shot (included with the purchase of V.D.) is optional, it just helps drive the V.D." "When tumbling obsidian, just go from 600 grit to the 25,000 V.D. and then to the 50,000 V.D. I did not see any benefit to using the 3000 V.D. when I tried it. Do not use the 800 aluminum oxide, as the stones do not take as good a finish with it for some reason. If you have 1000 silicon carbide grit, you could try that before going to the V. D. (recommended by Steve Hart of The Little Red Store on his web site) before going to polish, but I have not tried it yet." "I have had the best luck on obsidian without using pellets. When I used them in my vibratory tumbler, all they did was frustrate me and it took more time to tumble stones than without them. I do grind the chips and pits out on the grinding wheel after I run a batch through the 220 grit, but not every stone needs this. Then I put those stones that required grinding back into the 220 with a new batch. Again the V.D. provides all the cushioning you need, so no pellets are needed with it. I think I've had only one or two stones chip in the V.D." "I will tumble obsidian in 90-150 grit in my rotary tumbler rather than grinding stones before hand, then I'll go to 220 grit in the vibratory tumbler and then to 600 grit and then to the Vibra-Dry+." Again thank you Gary for your tips on using Vibra-Dry+! Anything that speeds up the tumbling process and is less of a mess for clean-up (Vibra-Dry+ uses no water in the tumbler, just the Vibra-Dry+ and stones) and takes a good polish is a welcome improvement!