jamesp
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Post by jamesp on Sept 19, 2014 10:32:40 GMT -5
I think there is a problem judging from the 24 hour photo below. It has to do with a large jump in polish size. Thank you for conversion chart Chuck. Here is basically the grit sizes used in microns: 30/60------250/500 220--------90 400/500----40/35 1000-------18 14,000------1 Look at the jump from 1000 to 14,000. It is 18 to 1. I will call Rock Shed to find out if their AO polish is in fact 14,000.(waiting for lazy westerners to wake up Shaun's girl thinks it is 4000. But also says it is 1.5 micron. That can't be. She is waiting for Shaun to come back. 4000 sounds better than 14,000 after 1000. Contacted them and they say 14,000. So will continue as long as needed. The other jumps range from 2 to 1 thru 5 to 1. And since the 30/60 was SiC(the 5 to 1 jump) had been run hard and fast w/out sugar, am sure it did break down. The 18 to 1 jump is a lot. AO 2000 would bridge that gap at about 9 microns. Looking at the pit depth and comparing it to the shiny high spots it looks like a ways to go:
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tkvancil
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Post by tkvancil on Sept 19, 2014 11:20:25 GMT -5
First off I've been following this thread daily. I appreciate the time and effort going into this. Photographic detail of the obsidian's surface has been enlightening to say the least. Coincidentally I have my obsidian batch going through the final stages as this thread continues. It has been interesting to see your progress as compared to what I'm experiencing.
Have been following Krystee's Ob tutorial with some degree of success. The 220 stage went well as far as I could tell. I think I put a little too much borax in the vibe as the slurry kept getting overly thick. Took more water to keep it going than I expected. Next I went to 600 SIC, don't have 500 AO. After 96 hours I did not have a shine anything near the picture in the tutorial. I decided to stop the 600 step here even though the tutorial said to maybe go a day or two longer. I had not seen any improvement from 48 to 96 hours. Made me wonder if the difference was something to do with SIC vs. AO.
I do have some AO 1000 so decided to try running it. In theory this is a big step backwards as the 600 SIC should have been something like 4000 by the end of 96 hours. A test pull today after About 24 hours shows that I'm getting closer to a finish that could be called shiny rather than matte. Makes me wonder about the nature of the breakdown of the two different grit types. Perhaps the sharp angular nature of smaller SIC particles do not lend themselves to creating a shine. Will have to order some AO 500 next time I get polish. Pretty sure that Chuck and Rob use AO for their pre-polish and their results are always awesome.
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jamesp
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Post by jamesp on Sept 19, 2014 12:32:08 GMT -5
Glad we are mirroring along tk. The vib is a sure success story on obsidian. Mentioning SiC, I wonder if it digs too deep or something. I read about AO being the preferred grit. So I avoided it except in coarse where the AO 220 could grind the scars away. And thought it did a good job, as it was a very soft frost when done.
Vib and rotary are far apart I suppose. I believe obsidian can scratch, and it is glass and we know what a glass cutter can do to it. The AO does round off. And the vib will sure round it. I would order some AO 500 from the Rock Shed. The AO 1000 may take a while to get rid of the surface from the SiC 600 as you mentioned.
Thanks for stopping by. Keep your progress posted.
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jamesp
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Post by jamesp on Sept 19, 2014 15:35:54 GMT -5
Checked @ 36 hours and shine is better. So still improving. Far away from the Lot-o though. Seems the large gap from 1000 to 14,000 is still an issue in a soft tumble. 1000 is 18 microns, 5000 grit is 4 microns, and this 14,000 is 1 micron. 18 to 4 is about 4 to 1 4 to 1 is 4 to 1 So a middle step of 5000 grit would reduce the step to less of a jump, right in the middle(by ratio).
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Post by mohs on Sept 19, 2014 17:58:04 GMT -5
intense display of rock'n photography!
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jamesp
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Post by jamesp on Sept 19, 2014 18:12:37 GMT -5
intense display of rock'n photography! Thanks Ed. Taking a rest and letting them roll.
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jamesp
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Post by jamesp on Sept 19, 2014 18:14:23 GMT -5
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Deleted
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Post by Deleted on Sept 19, 2014 20:28:29 GMT -5
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Post by rockpickerforever on Sept 19, 2014 21:03:14 GMT -5
I thought jamesp was the coral master? Coral King? Regardless, I'll give him a couple thumbs up for his work with this finicky obsidian. Good job, James!
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Post by nowyo on Sept 19, 2014 23:06:57 GMT -5
Missed a few days, finally got caught up again. James, the time you are spending on this and the attention to detail are amazing. Something to learn with nearly every post. Now I want to go back to Nevada and get a bunch of obsidian again.
I've only run a few batches of obsidian, I'm no expert. The photographic journey is incredible. Thanks for taking us along.
Russ
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jamesp
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Post by jamesp on Sept 20, 2014 5:28:03 GMT -5
Jean Scott and Russ, I do appreciate the thumbs up and newly acquired master designation. If you only knew the truth.
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jamesp
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Post by jamesp on Sept 20, 2014 5:56:11 GMT -5
Will try testing the gap between 1000 and 14,000. Since the 14,000 seems to be the biggest gap in 220,500,1000 to 14,000.
Will wet a piece of towel and spread 14,000 powder on it. Then take one of the stones that are presently tumbling and rub one side of it on the towel. Just to speed the slow tumbling process up and see if the 14,000 will in fact the job done.
Since the obsidian is soft it should easily lap by hand. Once the coarse step was done, hand lapping probably could have been done on the 220,500, 1000,and 14,000. Each on a separate piece of wet towel. To see if you ended up w/a wet shine and no scratches left. A quick test to check abrasive steps. If the hand lapping does not remove all scratches and end up w/a wet shine then most likely the soft tumble will not either. And you may find out which step required the most lapping.
I have a flat stone pulled from yesterday and will give the lap thing a try on one of the flat sides.
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jamesp
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Post by jamesp on Sept 20, 2014 6:14:24 GMT -5
A note on aluminum oxide cost, availability and types. There are dozens of lab grades that are expensive for precision lapping. Then there are sand blasting and tumbling grades that are cheap. At $16-$20 for 5 pounds of 500, 1000 and 14,000 the Rock Shed is a good bargain. It does not take much in these pre-polish stages. The 220 is common on ebay. If AO 4000/5000 is needed a source would have to be found. It is not common and seems to be lab grade grit so expensive. Probably a reason for not being available at tumbling suppliers.
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jamesp
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Post by jamesp on Sept 20, 2014 6:25:33 GMT -5
A note on obsidian availability. Sit on couch and wait for USPS to deliver LFRB to front door. That's how I got mine. Dave1 sent a LFRB of this fine sheen obsidian out of no where. We did not discuss it. We did not plan it. He just wrote "Here is some obsidian, send me some coral". Demanding old cuss. Dave not right. So began the obsidian journey. Thanks Dave.
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jamesp
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Post by jamesp on Sept 20, 2014 9:22:23 GMT -5
This hand polish trick is bang on. It will tell you a lot about your tumble. Took 3 minutes on a stone removed from the batch. Simply by rubbing the stone on a clean wet wash rag wit AO 14.000 polish sprinkled on it. Got a great polish quickly. But see problems. Today cloudy and cannot get a 'shiny shot'. Hand polish on left, another tumble to right, both pulled today. Rocks in tumbler getting shinier still, just slow. Please, no comments on pro photography. These were quicky hand held shots zoomed kinda close. No skill required. Only cropped. More of the above, just quick and easies: all using desk lamp. Notice problems on hand polished stone on left. It still has a fine polish to the eye though. Left pits behind somewhere along the way: Shot under clouds, not hand polished side : Hand polished side, and in sun it will sure shine, much shinier to naked eye: Ah, semi-sun came out, hand polished side, still cloudy: unpolished side:
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Post by iant on Sept 20, 2014 10:28:15 GMT -5
Getting great results here Jim!
Appreciate the time you are putting into this - lots of information for others to follow in your footsteps!
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Deleted
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Post by Deleted on Sept 20, 2014 11:27:57 GMT -5
Missed a few days, finally got caught up again. James, the time you are spending on this and the attention to detail are amazing. Something to learn with nearly every post. Now I want to go back to Nevada and get a bunch of obsidian again. I've only run a few batches of obsidian, I'm no expert. The photographic journey is incredible. Thanks for taking us along. Russ Cheaper to buy a FRB from catmandewe!
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jamesp
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Post by jamesp on Sept 20, 2014 11:28:00 GMT -5
Getting great results here Jim! Appreciate the time you are putting into this - lots of information for others to follow in your footsteps! I am cheating a little Ian. Using the same AO grit menu for hand grinding glass telescope lens. Since it is done by hand and takes a long time they use the friendliest abrasive and best grit steps. Except they use more steps than 100 240 400 and 1000, like 8 steps. I will be coming to visit soon Initial grit steps for telescope lens: "Fine grinding in this class uses a smaller progression of abrasives than normal 100, 240, 400, 1000. 8 wets each. A "wet" is the process of putting water and abrasive on the mirror and tool, then grinding the mirror against the tool until the abrasive is worn down. Use warm water for wets 400 and afterwards."
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Deleted
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Post by Deleted on Sept 20, 2014 11:30:10 GMT -5
You need a manicure
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jamesp
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Post by jamesp on Sept 20, 2014 11:49:09 GMT -5
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