Administered by Hale Sweeny (email@example.com)
This list digest contains the following message subjects:
1. LapDigest News for Issue No. 52 - Thurs. 8/28/97
2. NEW: How to Dye Howlite
3. NEW: Chrysoprase
4. NEW: Vibratory Lapping - A Weighty Question
5. RE: Vibratory Lapping
6. RE: Vibratory Lapping
7. RE: Vibratory Lapping
8. Re: POLISHING AMBER
9. BIO: Buddy Franklin
Subject: LapDigest News for Issue No. 52 - Thurs. 8/28/97
I had planned to devote one or more issues to vibratory flat
lapping, and had written several people on the list who I
knew did a lot of flat lapping, asking them how they did it,
and also asking several particular questions about it. Then
yesterday, I got a letter (below) from Bill Cordua, and
thought this was an ideal time to publish all those lapping
responses. So I want to thank Frank & Mona Frabbiele, David
H. Holmes and Ray Killian for their responses. We surely are
not through; everyone else with suggestions about vibratory
lapping is invited to send them in.
Subject: NEW: How to Dye Howlite
Ok, since we seem to be into the dyed stuff, here's one I
like to do for the flea market crowd.
Howlite is very easy to color. If you slab it using either
water soluble oil or just water, it will not end up with
areas that do not take dye. After you have shaped it up
you do not polish it. Heat it up to around 200 degrees in
the oven for a couple of hours to dry it out and then dip
it into your choice of colors. The cooling will help draw
the dye into the stone.
As to colors, lets see: Tidy Bowl in a concentrated form
gives you fake turquoise and Rit clothing dyes can create
all sorts of unusual colors. Soak the stuff for a few days
then rinse it off and after it dries a bit finish with the
Just be sure that if you give any stones away the folks
know its dyed howlite.
Subject: NEW: Chrysoprase
I would appreciate information from the members about
chrysoprase. What is the best current mail-order source for
good chrysoprase -- from medium to dark green and without
those little white spots? There seems to be some on the
market now, but I don't know what the quality is. I know
this material is a form of chalcedony. What chemical or
element is responsible for the color and what are those
white inclusions? Does chrysoprase usually come from
Australia? What is the maximum size one can expect without
too much of a premium? Thanks for any info.
"-- non-commercial republish permission granted --"
Subject: NEW: Vibratory Lapping - A Weighty Question
I'm doing some flat-lapping and am a real new-comer to that
field. Does any one have some suggestions as to good ways of
weighting down the slabs so that they will polish more
effectively? Thanks a lot all. - Bill Cordua
Dr. William S. Cordua
University of Wisconsin - River Falls
River Falls, WI 54022 715-425-3139
"Speak to the Earth and it shall teach thee" - Job 12:8
--non-commercial reproduction permission granted--
(Ed. note: Bill, I wrote to several people who I knew did
vibratory flat lapping, asking them several questions about
how they lapped. I have been saving their answers to make a
single issue devoted to this one topic, but this seems to
be the perfect place to bring them out. Their letters
How about it, gang, anyone else have suggestions for
weighting down slabs, or any other aspect of vibratory flat
lapping? -- hale)
Subject: RE: Vibratory Lapping
<<This letter is from Frank Frabbiele; I wrote him and asked
him to tell me how he does flat vibratory lapping.>>
Hale, in response to your query of "flat-lapping", I do
lots of it all year long.
I use a Riciprolap made by Rose Enterprise of Bakersfield,
CA. In my opinion, it is one of the best on the market, if
not THE best.
There are two sizes; I use the 20'', the other is an 18", I
believe. You will have to contact Mr. Rose to be sure. Two
functions are in progress at the same time: the entire plate
rotates, as well as vibrates. This allows material to be
lapped optically flat.
The 20" unit weighs about 150 lbs, and has rubber feet on
threaded stems,allowing you to level the unit from various
angles. (This unit will actually go through a sheet-rock
wall if not leveled properly before plugging it in.)
I start with 60/90 grit for material that is really hard,
or that has saw marks. For most petrified wood,and softer
rock, you can start with 220. After four hours,I remove the
material, and see if there are any obvious signs of not
being flat (where Hot Stuff has not been worn, or saw marks
not completely gone etc.). If not completely gone, I wash
off the surface, then take an aluminum scribe and make a
grid with quarter-inch squares all over the surface.
I replace the piece on the lap for 20-30 minutes. Then I
inspect, and if all the grid has gone, I can move on to 220,
500, 800 and polish respectively, using four hour periods of
lapping except for the polish. I use 8 hours minimum,and as
long as needed to produce a mirror finish. If there are any
questions, feel free to ask.
Regards, Frank for R&T
<<Thanks, Frank, for the information. I have heard that you
have to put rubber bands around the pieces being polished
to keep them from injuring/chipping one another. Is this
right? What do you use for rubber bands? Also, do you ever
add weights to rocks being polished? >>
Hale, rubber-bands are not used as they are too small etc.
What I do use is clear plastic tubing joined with wooden
dowels of the appropriate size, or rounded pieces of wood if
no dowels. You make the circles to the size of the base of
the rock + a little bit. This prevents the rock from
bouncing against it while under pressure,and eventually
forcing it off. This allows your rock to move freely within
the circle. Inside the plate is a bumper ring (I use 1 inch
tubing here) for added protection,and for large pieces (16"
in diameter is about maximum for the 20" model) lapping by
As for the weights,I use them occasionally only because no
adhesive I have found has worked as well as I would like.
When I do, I get door moulding in clay for from the hardware
store. I press the weight onto the rock with the clay in the
middle using lots of leaning onto the "sandwich" using my
body weight. I don't make thin slabs for the lap. I use a
high speed sander, or tumble them (up to a 12" slab) when
No I do not sell Rose lap, however, you may make your own
order with Mr. Rose at 805 872-0721 in Bakersfield,Ca. The
20" runs about $1300.00 +S&H + crating fee of ??
Hope this helped.
Frank & Mona Frabbiele <firstname.lastname@example.org>
Subject: RE: Vibratory Lapping
<<I also asked David Holmes to tell me about how he did
vibratory lapping; here is his response.>>
1st, answering your request for information on the use of
vibrating tumblers: I have several that I use to tumble
rock ends and pieces for friends and for packets given to
children by the Roxy Ann Gem & mineral Club in Central
The Grit sequence is as follows:
1st a combination of 60 & 90 grit,
2nd, a combination of 120 & 220 grit,
3rd, 600 grit, and
lastly, Cerium Oxide.
Depending upon the type of stones being tumbled (& slabs or
rough), each step requires approximately 72 to 100 hours.
The quality of the finished product varies, of course,
depending on the type of stones being tumbled. While many
of the stones are finished with excellent luster, the
overall quality is not as good as some of the tumbled
stones I see for sale at some rock shows. To attain that
quality it would be necessary to increase the number of
hours in each sequence.
2nd, a suggestion for rockhounds who use a flat lap to
polish larger stones: I have always had a problem with
rocks hitting each other in the lapping process and thereby
creating chips on the face of the rocks being lapped. The
problem was solved by purchasing some 3/8 inch tubing
(rubber or soft plastic) and some 3/8 inch doweling.
Various sized circles can be made with the tubing and the
two ends attached to each other by inserting the ends of the
tubing on the ends of approximately 1/2 inch piece of
doweling. It can be a tight fit so heating the ends of the
tubing to permit them to slip over the ends of the doweling
might be necessary. A single match will supply enough heat.
Tubing and doweling are inexpensive and following the above
procedure eliminates the problem of rocks hitting each other
when lapping several rocks of different size at the same
time. Hope this suggestion helps someone.
All of the foregoing is non-commercial and permission to
republish is granted.
David H. Holmes cjmr94a@Prodigy.com
Subject: RE: Vibratory Lapping
Hale, you have asked the most important questions I can
think of. Will try to answer them for you.
....Types, manufacturers and sizes of Vibratory Lappers
I only have used two different laps. One made by Lortone and
the 27 inch VI-BRO-LAP made by Highland Park. I did not have
too good luck with the Lortone but then that was my first
attempt to do lapping. When I got the Vi Bro Lap I got
Lortone was 12 inches and the Vi Bro Lap was 27 inches;
there are lots of difference in operations of the two. As I
was interested in making large clock faces, I have more
experience with the bigger lap.
....How to use them - in general
Not hard to use, there are several things one must do to
have good luck with lapping.
MAKE SURE THE LAP IS LEVEL!! This is very important; if not
level all material will want to go to one side and not
rotate. If your item does not rotate, no polish will take
Do not run lap dry!! And I might add not too wet. Laps that
are too wet tend to make a mess out of everything around.
You have to have some kind of bumper to keep items from
chipping when hitting each other.
My saw runs fairly true and does not leave deep marks, I am
able to go to lap with 600 grit keeping the wet grit on
the thick side about like cream. Then to polish not too wet
just so stones will move freely on lap.
....Problems of thin/light weight sections
Clock faces or slabs (1/4 inch thick): I made disks out of
3/4 inch plywood and attach lead weights. Disks range from
5 inches to 12 inches in diameter. Lead weights I made
using a 6 inch skillet for mold. This can all be done on
top of stove. Melt lead in skillet and let cool, one weight
at time. These will weigh about 5 to 6 pounds each, bolt to
plywood disk. Lead weights I found work the best, altho I
have tried about everything.
Using double back tape (kind used to hold rugs in place),
tape the slab to a plywood disk, making sure no part of slab
extends past the edge of plywood disk.
You are ready to start lapping. I have had good luck with
this method. One weigh on small disks and two to three on
larger ones. If it bounces add more weigh.
I have tried other ways, but this seem to give me less
trouble. Hose or tape did not work for me on thin slabs.
....Problems of large heavy sections
Had no problem with heavy sections, such as book ends. As
long as the item doesn't bounce and it rotates it will
polish. Sometimes one can put only one item at a time on lap.
I hope I have answered your questions about flat lapping. I
have tried to cover the basics, we each must take these and
find out just what will work for them. Lap must be level -
Don't run dry - if bounces add more weigh - don't let items
hit each other.
Editor of The Nisqually Rockhounder
P O Box 6 Cle Elum WA 98922-0006
NON - COMMERCIAL REPUBLISH PERMISSION GRANTED
Subject: Re: POLISHING AMBER
In Issue #49, Richard responded to a query about how to
polish amber with the following:
<<An easy way to polish Amber without damage and without
losing size and weight is with the simple tools most
Lapidaries have. What worked for me and Sapphire Gems of
Miami, was a soft leather such as chamois, and Cerium oxide.
The leather was dampened and the Cerium made into a light
slurry. Course, hand lapping (polishing is the order of
the day) takes a few more minutes than a cab machine, but
assures you of nice finish without destroying the various
contour of the amber.....Works for me..... Richard>>
I agree with Richard about the hand-lapping part. While
I've got lapidary arbors of various types, I find that amber
is not very amenable to being treated like a rock. Diamond
equipment doesn't seem to work very well either for sawing,
grinding, or polishing, and dopping can be a disaster.
Amber is extremely intolerant of heat, and just a little too
much pressure while polishing can leave ugly mars on the
surface. Especially with valuable specimens, like
insect-included ones, the extra time spent initially in
removing material by hand with files and sandpaper is made
up for by the increased control of the surface and not
having to start sanding all over again to remove heat-scars.
The hard part with this stuff is to avoid removing too much
too quickly. Once you have gotten down to 600 grit by hand
(I like silicon carbide wet-and-dry paper), it can be
polished by stroking the piece against some leather or
cloth charged with a plastic-polishing compound. (I've
heard some people swear by cigarette ashes for polishing,
but I haven't tried this.)
I'd like to hear some alternatives to the dop-pot approach
for holding onto small pieces, since amber responds as badly
to being flung about as to heat- has anybody tried hide glue,
(which is water resistant but dissolves in alcohol) often
used by woodworkers for items which are to be disassembled?
What about warm beeswax?
Andrew Werby - United Artworks
Sculpture, Jewelry, and Other Art Stuff
Date: Wed, 27 Aug 1997 08:44:52 -0500
Subject: BIO: Buddy Franklin
Hello my name is Buddy Franklin , I live in central Alabama,
close to Birmingham and I am just getting started in
lapidary as a hobby , I have had an interest since I was
young. My uncle is a rockhound and he is who got me
interested . I don't have any equipment as of yet but I am
about to join a local club and hope to get educated more
before I buy. I am here to absorb as much knowledge as
possible , I am sure I will have many questions. Until now
I have just collected rocks (mostly bought some found )and
that is as far as I have been in this hobby but I am ready
to go a lot further now. See ya around ;)
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