ddimatteo
off to a rocking start
Member since July 2010
Posts: 2
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Post by ddimatteo on Jul 18, 2010 8:41:41 GMT -5
  Hello all. This is my 1st time with obsidian I got from Flagstaff. Using rotary tumblers, obsidian only. Where did I go wrong?, this is the final burnished (ivory soap) product. Did all 4 steps, my other batches seem ok, same stone. Using 3lb, 4.5lb and 12 lb tumblers, plastic pellets, etc. Polished 5 days, soap 3 days. Any suggestions? Thanks, Dennis |
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Sabre52
Cave Dweller 
Me and my gal, Rosie
Member since August 2005
Posts: 20,504
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Post by Sabre52 on Jul 18, 2010 13:49:36 GMT -5
OK, Obsidian is a difficult material for me too. First off, the example in your first pics looks pretty porous. That sort of material is disappointing no matter how you work it. Next, with obsidian you should tumble it a long time in rough to get the stones well rounded, they tend to chip and ding if you leave the edges you have on your stones. Third: do it strictly by itself with no harder rocks, use lots of plastic beads and even thickeners if necessary. Works better in the smaller smooth types of barrels too as the faceted barrels like the larger Lortones drop the stones against each other too much. Full loads are better too as again, less bopping together of stones. Aside from that, just normal recipes. I'm sure some of the folks better at obsidian than I will have more help for you.....Mel
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Post by jakesrocks on Jul 18, 2010 14:00:08 GMT -5
Obsidian is best done in a vibratory tumbler. A rotary tumbler will allow the stones to ride up the side of the barrel and fall back down on top of each other. This is after all a volcanic glass, and as such is prone to easy chipping.
Don
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Post by montanamuskrat on Jul 18, 2010 23:49:33 GMT -5
We have done Obsidian in both rotating tumbler and vib tumbler. We agree with Mel on all points. We used cerium oxide and got fair results in the rotating tumbler. One barrel had to many large stones and came out like yours. We mixed small and large and filled the 3/4 full with good results. We have pics of the batch done in the vib tumbler. They turned out a lot better.
Debby & Tom
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Post by susand24224 on Jul 19, 2010 0:33:52 GMT -5
I've done obsidian in a rotary. Key points:
1. I added a few TB of borax in each step (this has proven to be an effective thickener for me).
2. I used about 1/3rd volume ceramics. Plastic may work well, but I don't like using plastic pellets, so I only do so when ceramics don't work.
3. I polished with Rockshed AO, but it took about three weeks.
Susan
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ddimatteo
off to a rocking start
Member since July 2010
Posts: 2
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Post by ddimatteo on Jul 19, 2010 7:01:04 GMT -5
Great recomendations everyone, I've redoing batch in vibratory with soap, pellets, ceramics-pre-polish 500 grit, for the next 48 hrs and then trying polish. As a Newbie, not familiar with Rockshed AO? Thanks for the help everyone.. Dennis  |
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Post by Hard Rock Cafe on Jul 19, 2010 8:56:30 GMT -5
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Post by 150FromFundy on Jul 19, 2010 11:12:19 GMT -5
In addition to the normal 4-stage grit/polish sequence, add a stage of 1000 AO before the polish. This is often done with softer stones like obsidian, apache teardrops, etc.
When I use a vibe for this material, I use 25% to 50% ceramic media.
Darryl.
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Post by frane on Jul 21, 2010 18:17:49 GMT -5
Any time I have had good results with obsidian, I have had to use filler. I will admit that with glass or obsidian, I use it in every step, even roughing it out because too many dings and you can't seem to get rid of the fracture in the stone. I ended up with the white edges on one of my loads when I had too much water in it when using plastic pellets. The pellets float so they didn't stay where the stones needed them to be. I had better results when doing them in a rotary when I used tile spacers as filler because they do not float. In a vibe, I use about 50% ceramic filler with obsidian.
Just toss them back in and run them. You will get there!
Fran
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