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Rats
Jun 16, 2016 19:50:33 GMT -5
meviva likes this
Post by Toad on Jun 16, 2016 19:50:33 GMT -5
Tried polishing obsidian using just ceramic media. Frosty as heck on the edges. Back to 220 using only airsoft pellets. Will update when warranted...
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Rats
Jun 25, 2016 9:20:33 GMT -5
via mobile
Post by broseph82 on Jun 25, 2016 9:20:33 GMT -5
Tried polishing obsidian using just ceramic media. Frosty as heck on the edges. Back to 220 using only airsoft pellets. Will update when warranted... Lighten the load maybe?
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,681
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Rats
Jun 25, 2016 9:58:42 GMT -5
Post by Fossilman on Jun 25, 2016 9:58:42 GMT -5
LOL-I have trouble getting the polish to hold on Obsidian too....
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Rats
Jun 25, 2016 15:01:20 GMT -5
Post by Toad on Jun 25, 2016 15:01:20 GMT -5
I have way more pellets than obsidian by volume. Had to cull several large pieces with problems as I went through the different grades.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,155
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Post by jamesp on Jun 25, 2016 21:02:56 GMT -5
Obsidian has whipped me many times. Don't feel bad. Get a Lot-O, best advise I know.
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Rats
Jun 25, 2016 22:18:52 GMT -5
via mobile
Fossilman likes this
Post by Toad on Jun 25, 2016 22:18:52 GMT -5
Never planning to get a vibe but may reconsider.
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Post by susand24224 on Jun 26, 2016 0:03:24 GMT -5
Toad, I've never used anything but ceramic media with obsidian. The key, at least for me, is to slow the action down--adding soap or something else to thicken the water. Also, I used like 2/3rds or so ceramic media and 1/3rd obsidian. I've done obsidian in both rotary (pre-Lot-O) and Lot-O; pretty much the same procedure. You can also add a little extra water to cushion, but if you do the polishing will take much longer. It usually takes me 2-3 weeks to get a good polish on obsidian anyway.
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jamesp
Cave Dweller
Member since October 2012
Posts: 36,155
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Rats
Jun 26, 2016 3:15:51 GMT -5
Post by jamesp on Jun 26, 2016 3:15:51 GMT -5
Never planning to get a vibe but may reconsider. The best I have ever done was in a rotary. Never a great shine though. Tried in my Viking vibe and can't get it right-bruises.
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Fossilman
Cave Dweller
Member since January 2009
Posts: 20,681
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Rats
Jun 26, 2016 9:23:37 GMT -5
jamesp likes this
Post by Fossilman on Jun 26, 2016 9:23:37 GMT -5
I get the smoothness,but not the polish.......Will try Susan's theory..
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Rats
Jun 26, 2016 13:33:36 GMT -5
Post by Toad on Jun 26, 2016 13:33:36 GMT -5
Susan - I had plenty of ceramic media and I used plenty of polish as thickener, it was full to the top. Still wondering what went wrong...
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tbvet3
starting to spend too much on rocks
Member since March 2016
Posts: 123
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Rats
Jun 27, 2016 12:51:23 GMT -5
Post by tbvet3 on Jun 27, 2016 12:51:23 GMT -5
Might try adding some corn starch or flour like your momma did to thicken gravy. No worries, the lumps will go away.
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Post by Toad on Jun 27, 2016 14:46:24 GMT -5
Going back to 220 got rid of the frosted edges. Moving on to 600...
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riverrock
fully equipped rock polisher
Member since April 2010
Posts: 1,395
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Post by riverrock on Jun 27, 2016 15:53:26 GMT -5
I keep working on a 15 lb batch. It's a hard one to get a shine on, we feel your pain.
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Enigman
starting to spend too much on rocks
Member since December 2013
Posts: 163
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Rats
Jun 27, 2016 16:25:30 GMT -5
Post by Enigman on Jun 27, 2016 16:25:30 GMT -5
Edge frost is usually from excessive "fall impacts". The best bet is to fill the barrel to within an inch to inch and a half or so of the top with at least as much media as obsidian. That decreases the "fall distance" of the obsidian.
After two years of trial and error I have finally landed on a formula that now works every time, no frosting, and ends with a super glassy gloss. I use rotary machines for the 60/90, 120/220 and 500 grits, filled as above, then the polish stage is done in a Diamond Pacific MT4. It polishes for 6 to 7 days and comes out super high gloss ... every time. I am running every type of obsidian now with no problems.
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The Dad_Ohs
fully equipped rock polisher
Take me to your Labradorite!!
Member since September 2012
Posts: 1,860
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Rats
Jul 12, 2016 13:45:11 GMT -5
Post by The Dad_Ohs on Jul 12, 2016 13:45:11 GMT -5
I've down almost all of my Obsidian in my rotary, QT66, and it has taken some time to figure out something that works for me.... when I finish tumbling my course stages, I dump the slurry into a bucket and leave it out for the water to evaporate. I then re-use the powder when i do my next batch of rough. I add about 2 heaping teaspoons of this powder back into the barrel, in addition to the regular amount of grit for the grind. This tends to cause the slurry to form faster and thicker than normal which cushions the Obsidian while tumbling. when I get to the pre-polish stage I switch from ceramic to plastic and use borax with the grit, again to thicken the mix. Same goes for the final polish. the name of the game with Obsidian and a lot of other stones is to cushion/minimize the bruising throughout ALL the stages, not just the final. the bruising will not be easily removed in any of the later stages after 120.... same goes for amethyst and quartz types.
I now use a vibe for polish on Obsidian... got a cheapo from HF for about 49.99 that works well for a single stage and I am getting an extra bowl for some courser grinding of different materials.
hope this helps some!!
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