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Post by gmitch067 on May 2, 2018 1:47:06 GMT -5
I hand-cab and tumble and have a love-hate relationship with green Aventurine. Some of the slabs I have worked with have an abundance of those small plate-like inclusions across the face that sparkles soooo beautifully, but are sooo difficult to polish when hand-cabbing or finishing cabs in a vibratory tumbler. I found that using SiC wet/dry sandpapers to shape and finish the cabs is the safest way to optimize the final results (remember… "hand-cabbing")… 80-220-400-600-800-1000-1500-2000-2500-3000-5000 grit(s) followed by application of Tin Oxide using a dremel polishing wheel… Still, the surface of the finished cab is rough in texture across the areas of inclusion. So… Now I go through all the sanding and then run them in a TO polish with the Lot-O… Much better shine but the inclusions are still noticeably rough to the touch. …tedious and hurts my arthritic hands. Question for all you Hand-Cabbers out there: Is there another way to address this problem… that will allow a good even shine across the areas of inclusion? Here are some pics to illustrate the inclusions. Using the Aventurine (with the inclusions) in a rotary tumbler is also a disaster Glenn
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Deleted
Deleted Member
Member since January 1970
Posts: 0
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Post by Deleted on May 2, 2018 2:20:58 GMT -5
The sparkles are mica (fuschite), which are much softer than the quartz body. Best to treat this like other mixed-hardness stones that severely undercut. For me, that means skipping coarser grits and using a light touch to avoid crystal tearouts (which are hard to sand out later), then foregoing soft wheels, buffs and/or pads. Polish (and not too much of it) on hard leather, maple or something even more rigid that is less prone to pressing down and undercutting those soft mica flecks.
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Post by gmitch067 on May 2, 2018 6:40:19 GMT -5
The sparkles are mica (fuschite), which are much softer than the quartz body. Best to treat this like other mixed-hardness stones that severely undercut. For me, that means skipping coarser grits and using a light touch to avoid crystal tearouts (which are hard to sand out later), then foregoing soft wheels, buffs and/or pads. Polish (and not too much of it) on hard leather, maple or something even more rigid that is less prone to pressing down and undercutting those soft mica flecks. Thank you @rocks2dust. I guess I need to go back to the good ol days of hand polishing on a strip of cow hide instead of using a dremel... darn!... there goes my fingers again! I can also remove the pad of hard foam rubber from below my sheet of sandpaper... less give.
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Post by rmf on May 2, 2018 6:58:59 GMT -5
Have you tried to grind it down to 220 then dry it and hit the top with cyanoacrylic and then ground it off. I have had to do that with rutilated quartz to keep the rutile from pulling out as I cut it. they make a water thin CA that fills pores and cracks well.
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Post by gmitch067 on May 2, 2018 10:18:38 GMT -5
Have you tried to grind it down to 220 then dry it and hit the top with cyanoacrylic and then ground it off. I have had to do that with rutilated quartz to keep the rutile from pulling out as I cut it. they make a water thin CA that fills pores and cracks well. worth a try rmf. I have some Starbond thin/fast that should work. The top two 30x40mm ovals shown in the pic have deep pits and have been worked twice already. All cabs shown are down to a 4mm thickness... their back sides also show inclusions. I can work them, but lack a gentle touch... The Starbond might give them the strength to survive. With my arthritis going a bit crazy now, I might have to put this on hold for awhile (with 3 fingers on my left hand and 2 on my right hand not able to bend, hand cabbing and wire wrapping are becoming a challenge... I might try to dop the cabs on giant dowels... but still must grip it... Hmmm... another challenge!) Glenn
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goatgrinder
spending too much on rocks
Make mine a man cave
Member since January 2017
Posts: 368
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Post by goatgrinder on May 3, 2018 19:26:02 GMT -5
Stop it. They look fine so run with them. I tell my students that writing is easy because they decide when to stop.
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Post by gmitch067 on May 3, 2018 20:48:44 GMT -5
Stop it. They look fine so run with them. I tell my students that writing is easy because they decide when to stop. So the inclusions are acceptable in jewelry???
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goatgrinder
spending too much on rocks
Make mine a man cave
Member since January 2017
Posts: 368
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Post by goatgrinder on May 4, 2018 12:07:42 GMT -5
IMHO:
Think of the most beautiful corals and agates and other gems that you have seen and ask yourself how grinding all interesting features out of any stone would make it anything but boring. A gorgeous stone will always be desirable. Honestly I admire the finished stones in your pic. Yes they are lovely and acceptable as pieces for jewelry. If perfection could be obtained how would it make these stones any more attractive?
Long live the Pink Panther.
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Post by gmitch067 on May 4, 2018 12:46:41 GMT -5
Thank you goatgrinder. Your comments have given me food for thought. Maybe my ideas of what a cab should look like should be re-evaluated. The ones I see other members post are so perfect in shape, composition, and polish that it has influenced me to set unrealistic goals for every stone type or composition... Especially as a Hand-Cabber. However... the rotary tumbled stones DO look terrible! Lol! Thankyou again. Glenn
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