Bains
off to a rocking start
Member since December 2004
Posts: 12
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Post by Bains on Mar 17, 2014 11:23:47 GMT -5
I may be over-thinking this process but I thought the forum could help.
I am a newbie to tumbling. I have my first bunch of material which is a mix of undisclosed origin but probably agate material in the pre-polish stage. It is in a vibratory tumbler.
I have a second batch in the coarse grit stage – hickorite and labradorite with are supposed to be essentially equivalent Mohs hardness values. Additionally there are some additional material of undisclosed origin but assumed to be harder. My intention is to focus eventually on the hickorite and labradorite. All of this material is in a 12# rotary tumbler.
Using a 10X jewelers loupe I can still see some pits in the hickorite and labradorite.
Looking at the first batch, they look OK but under examination there are some minor pits as well.
So do I just keep grinding until no pits or is there some point where you move on and live with small imperfections?
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Post by Hard Rock Cafe on Mar 17, 2014 13:23:49 GMT -5
I've found that with pitted material the pits never go away; more grinding just reveals new pits. BUT, if you're not loading your vibe with enough material that could be causing the pits. That happened to me when I started with my vibe. The rocks act like tiny hammers and beat on each other if you don't have good circulating action.
If you try to polish softer rocks with harder rocks, the harder rocks will polish but the softer rocks will not (they'll just grind away).
Chuck
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Post by 150FromFundy on Mar 17, 2014 17:36:53 GMT -5
In addition to what Chuck said, for softer material, you need plastic pellets in the rotary and ceramic pellets in the vibe. When polishing cabs in the vibe, I use a bowl full of ceramic pellets and a handful of cabs in an effort to ensure that the cabs never contact one another.
You also need to separate softer material and not mix it with other rocks. This is especially true with Obsidian (Apache Tears), and your Labradorite, which is a fancy feldspar.
For a newbie, you have picked some tough material to work with. Ironically, hard rock is easy to work with and soft rock is hard to work with. You have chosen some soft rock which is not the easiest material to start with. If your end results don't meet your expectations, don't give up. Next batch, stick with harder agates and jaspers. When you have perfected those, move on to softer material as your experience grows.
Good luck.
Darryl.
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Post by deb193redux on Mar 17, 2014 19:29:59 GMT -5
if you can cut one in half, you can judge if pits go through - or, hand grind a flat face on one with grit on a glass plate. can you get past pits?
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Bains
off to a rocking start
Member since December 2004
Posts: 12
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Post by Bains on Mar 18, 2014 15:37:57 GMT -5
deb193redux asked about depth and suggested hand grinding or cutting. Well, at this time I have neigher a grinding or cutting capability.
Using a 10X jewelers loupe I can still see some pits in the hickorite and labradorite. 10X is lot of magnification. When I look the pits are pinhole size and they do not go far into the rock -- just pinholes that are pinhole deep as well.
For all I know, the rocks are honeycombed with these small imperfections -- that is why I asked the question since I have no experience base.
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Post by deb193redux on Mar 18, 2014 19:30:40 GMT -5
anyone can put some grit and water on a pane of glass and use elbow grease. it is essential to determine if pits are on surface (and possibly produced by your tumbler) or honeycombed through.
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Post by pghram on Mar 19, 2014 13:30:33 GMT -5
If you need the loop to see them & they are eye-clear, you may not need to worry about them. I would let them rough another round or two & then proceed through the grits & polish.
Rich
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Post by Hard Rock Cafe on Mar 19, 2014 14:13:35 GMT -5
What Darryl said: Lake Superior, Brazil, or Montana agate is a lot easier to learn with because it's very hard.
Chuck
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