LAPIDARY DIGEST
Administered by Hale Sweeny (hale2@mindspring.com)
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This list digest contains the following message subjects:

1. LapDigest News for Issue No. 42 Saturday 08/09/97
2. RE: Polishing Tiger Eye
3. RE: Polishing Tiger Eye
4. RE: Polishing Tiger Eye
5. RE: Polishing Rainbow Obsidian
6. RE: Polishing Laboradorite
7. RE: Polishing Laboradorite
8. AD: Agate & Petrified Wood
9. BIO: Grant N. Newbold


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<MSG1>
Subject: LapDigest News for Issue No. 42 Saturday 08/09/97

Please remember to add the words "non-commercial copy
permission granted" at the bottom of each posting you
make. This will allow gem clubs to copy threads for their
newsletters.

Please send any lapidary 'tips' you have to me at the
address shown above. These will be valuable as 'fillers'.

I would like to hear from any of you with experience in
vibrating lapping machines - just tell me what kind of
machine(s) you have, and what material you polish. Let's
do a whole issue on "how to use a vibrating lap". Among
the 325+ members must be lots of members with experience
in this whom we can draw on for help.

Also if you have vibrating lap questions, please send them
in; I will try to make sure they are answered in the
vibrating lap issue.

Have a great weekend! Stay safe.. be careful.. have fun!

hale
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<MSG2>
Subject: RE: Polishing Tiger Eye


(MSG3-8/7/97} on Polishing Tiger Eye: <snip>
The bottom line is that I've not yet been able to get as
nice and as even a polish as I've seen on tumbled tiger
eye or on cabs I've seen at Federation shows.
What's the secret, guys ?>

I have found that finish sanding on a worn 600 grit
sanding belt then polishing on hard leather with linde A
mixed with a little vinegar works well. You may be pulling
the stone apart with the finer diamond grits. Also spend a
little extra time on the sanding steps, especially 400 and
600 grit.

Cerium oxide just dosn't seem to work well on tiger eye.
You might try some other expanded alumina polishes on soft
or hard leather. The stone should get very warm when
polishing, so be careful that you don't melt the dop wax.

Earl English
ewenglish@blueridge.net

non-commercial republish permission granted
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<MSG3>
Subject: RE: Polishing Tiger Eye


G'day; I've been cutting, polishing, and shaping various
materials for about 25 years. The method I was shown by
professionals in the jade factory at Hokitika, New Zealand
gives a brilliant mirror polish, not only on jade - which
most people agree is difficult, but on everything else I've
tried, inclding tiger-eye.

After going through the usual grades of wet/dry paper stuck
to thin foam rubber backed with an 8 x1/2inch inch MDF disc,
you get a pre-polish with dry 400 grit.

Change to a disc with a piece of old leather stuck to it -
I used a piece of an ancient school satchel, rough side out.
Paint this with a slurry of tin oxide, and have the disc
turning at around 800 rpm - not too important, but it
shouldn't go too fast or the slurry will fly off. Press
hard, keeping the work moving with a flexible wrist movement
and soon one finds the work begins to drag on the lap, and
that moment is when the true polish starts. And as I said,
you'll see your face in the workpiece, but don't of course,
let it get hot enough to melt the dopping wax or other
cement.

The thing is, don't skimp on the preliminary work with the
papers. I start with 180, then 240 and finish with 400 dry
or sometimes 600 dry. I have used diamond but only in the
little places on intricate carvings where the big lap won't
work. Try tin oxide on leather.

John Burgess,
johnb@ts.co.nz
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<MSG4>
Subject: RE: Polishing Tiger Eye


You have to think of tiger eye like wood. You have to sand
and polish across the grain. If you go with the grain you
will rip up those little fibers and it will show as pits.
If the ends are rough from not quite getting them on the
belts you should give it a little hand sanding. Some of the
best stones I've seen have been hand sanded. For a finish on
quartz material you can't beat tin oxide on a hard felt wheel.


Steve Ramsdell
sramsdel@prairienet.org
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<MSG5>
Subject: RE: Polishing Rainbow Obsidian


<< I am looking for some help from other members who may have
had some experience polishing rainbow obsidian. (snip)>>


The 80 grit might be part of the problem, it will leave stress
fractures that extend into the stone and you might not grind
far enough to remove them. Even a 260 will leave some minor
surface fracturing. Remember what you are doing is gouging
out scoops of the rough as the diamonds make contact and this
will cause cracks and fracture lines that extend into the
stone. Also obsidian can have lots of small inclusions,
both air cavities, and trash that might be parial
crystilization or something that the flow picked up.


Ken Wetz
kwetz@acun.com
http://www.acun.com/~kwetz
+-------------------------------------------------------+
(Ed. Note: Ken's explanation sounds so reasonable for
obsidian that it makes me wonder what other materials behave
this way, and what are the properties of the materials which
make them behave this way - conversely, why don't all
materials behave this way? -- or, do they? hale)
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<MSG6>
Subject: RE: Polishing Laboradorite

<<I would also like some advice on polishing labradorite to
a beautiful finish like the specimens currently coming out
of Madagascar. I have tried using all the nova wheels through
50,000 and the finish is fair at best. The pieces coming out
of Madagascar look like the finish is "melted", almost as if
the pieces were polished using a compound at a high speed or
temperature. Has anyone had any experience with this material?>>

I use cerium on a disk made from cotton canvas and it seems
to do a good job for me.

Ken Wetz
kwetz@acun.com
http://www.acun.com/~kwetz
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<MSG7>
Subject: RE: Polishing Laboradorite


Try using tin oxide on a rock hard felt wheel. If you don't
want to invest in a large felt wheel, many jewelry supply
companies stock 3 inch that fit on polishing arbors (tapered
spindles). The little ones are a few dollars, while the big
wheels could cost $100.

Steve Ramsdell
sramsdel@prairienet.org
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<MSG8>
Subject: AD: Agate & Petrified Wood


1.)I have an opportunity to buy several hundred pounds of
Brazialian agate (raw). It appears to be in about 6-10 pound
pieces. Can anyone tell me the going price for Brazilian
agate rough?

2)I have a lot of good to fair petrified wood (miscellaneous
colors) and agate (mostly clear) in small to medium pieces
that I would like to get rid of--any interest? I live in
Victoria Texas.

smitty
smitty@tisd.net
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<MSG9>
Subject: BIO: Grant N. Newbold


Hi Lapidary Digest

I am 46 years old and am currently attending Wright State
University in Dayton Ohio to obtain a doctorate in clinical
psychology. I have only been in Ohio for one year and am
originally from Nebraska where I was a farmer and a biology
instructor at a community college.

I am not currently doing much in the way of lapidary but I
am seeking information on making beads from domestic stones.
I hope to get into that aspect of the hobby in the next few
years and then to do more of it as I approach retirement.
Since I actually want to cut the stone, then make the beads
myself, and then drill the holes in them, I am seeking the
information on this digest rather than the jewelry digest.

Thanks

Grant Newbold
s001gnn@discover.wright.edu
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