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Ancient intarsia techniques


#1

All,

I’m researching how to do intarsia gemstones because that is one of
the things I eventually want to do.

So far I have been trying to figure out how they were created before
the modern age, because I do not want to deal with using epoxy… it
would seriously detract from the value of any intarsia gemstone which
I might attempt.

However, there do not seem to be any publicly searchable methods or
techniques on the classical intarsia methods. The only hint I have
been able to glean was to use pins of some type.

I otherwise have had to consider first principles once I started
considering pins.

So far I am thinking I might need to carve relief patterns into the
base mineral to fit with grooves in the which I could
possibly do the the necessary accuracy with CNC.

But, the problems with that as far as I can see, is that the design
would neither be stable along the edges nor along the Z axis. Then I
thought of using dovetail joints, but the problem with that is that I
cannot find a diamond point inverse cone whose angle is precisely 45
degrees.

Could any master of classical gemstone intarsia please possibly
consider giving me a few hints as to how joining used to be done
before adhesives, so I don’t have to be more ultratech about creating
mechanical joins this than I absolutely have to?

Thanks in advance,
Andrew Jonathan Fine


#2
Could any master of classical gemstone intarsia please possibly
consider giving me a few hints as to how joining used to be done
before adhesives, 

Andrew, I’m certainly not such an expert, being introduced first to
intarsia work in the 60s, and it was all then done with epoxy. And I
myself didn’t do it much of it then, and none now in any case. But
it occurs to me to mention that “before adhesives” is a VERY long way
back. Not epoxies, but various gums, tars, plant and animal glues,
etc, go back just about as far as recorded jewelry history… I’ve
seen what seem clearly to be adhesives in Egyptian jewelry/metal
work (look up inside the famous mask of king tut next time you’re in
the Cairo museum), Roman, even even ancient Sumarian work… And
logic suggests to me that ancient workers, using even less technical
tools available to do intarsia that we’ve got now, probably would
have looked for simpler means than cutting invisible dovetails along
the edge of minute fragments of stone. Are you so sure that adhesives
weren’t used in the work you refer to?

Peter Rowe


#3

John Donivan posted a web address for work (lapidary) done in Italy
not too long ago.

“Pietra dura” is the Italian word for that sort of lapidary work and
they are justly famous for their skills.

That would give Andrew more info. Adhesives were used for ages;
sometimes called mastic.

Google is a very useful avenue in finding basic info.

KPK


#4
how to do intarsia gemstones because that is one of the things I
eventually want to do. 

Andrew, Andrew, Andrew… Stone work is lots of fun, I think - I
used to run an inlay shop, and kept it up for years after that -
wouldn’t call myself a master, that’s for sure…

First, if you haven’t already, see my blog here:
http://johndonivan.ganoksin.com/blogs/

Where there are some pics of a tour of a pietra dura shop in
Firenze, Italy. You may notice the absence of CNC equipment…

because I do not want to deal with using epoxy... it would
seriously detract from the value of any intarsia gemstone which I
might attempt. 

Peter said some things today, to begin with… The shop in my blog
said they use beeswax, though I suspect it’s a proprietary mix with
beeswax as a base. If you truly believe that epoxy is somehow going
to “detract fromthe value” then I won’t argue with you, but I don’t
see how and I’ll tell you flat out that you will find no more
perfect adhesive for the job than epoxy, especially if it’s to be
worn, as in jewelry.

Small scale inlay (I call it “inlay” as a generic term, and there
are many forms) is either fitted into metal shapes and ground flat
or is fitted together, stone to stone, and then ground flat. Mosaics
are usually done incrementally - cut some and glue it, cut some more
and glue that - you can’t work with fifty little pieces…

Larger scale mosaics, like table tops, are slabbed, sawn and fitted,
and then thinner pieces (like lapis) might be blocked up from the
back to make the height equal. The are sanded and polished smooth,
but usually the height is as close as can be gotten from the
beginning, else the grinding is monumental and wasteful.

Some pictorial pieces aren’t even backed, they just have glue blocks
holding the pieces together… Much to know, much to learn…


#5

I’ve actually worked on a few old pieces over the years, and I swear
they were held in with a cow dung and beeswax mixture. Really.

Have fun and make lots of jewelry.
Jo Haemer
www.timothywgreen.com


#6
I'm researching how to do intarsia gemstones because that is one
of the things I eventually want to do. 

I’m not a master, but pre industrial techniques are a particular
hobby of mine.

Bear in mind that most of the references to the “grooving” of the
pieces is referring to works primarily in materials like marble.
Which was one of the more popular mediums for Pietra Dura. For the
most part, these forms of intarsia were set on a base plate unlike
the backless intarsia that is commonly done today (a method that only
really became practical with the introduction of modern adhesives).
The more portable items were done on metal backing plates.

Some surviving jewelry pieces that have lost stones and had the
remaining adhesive analyzed show calcium carbonate based cement,
Theophilus in the 12h centuy, made references to using resins like
frankencense as an adhesive to bond bone knife handles to the knife
shank. A pretty broad array of adhesives common in the 1400s can be
found in the _Craftsman’s Handbook" by Cellini.

I’ve used a home made hide glue to bond a stone to a bone substrate
that stood up to years of wear (it got re-glued 8 years after being
made).

There’s more, but that’s what was within easy desk reach.

Ron Charlotte – Gainesville, FL


#7

Hi Andrew. If you’re trying to use ancient techniques, I’m wondering
why epoxy is a no-no but CNC is OK?

Allan


#8

Allan,

I had merely said I had wanted to research ancient techniques on
assembling intarsia. I had been wanting to look and see if the
ancients had used any glueless techniques.

I had thought that perhaps today’s gemstone intarsias were being
bought and sold that had been assembled glueless but that the
masters had been holding thier secrets to close for me to google out a
stray remark.

It seems now that glues have been used recorded history and
therefore seem the only way possible to assemble composite gemstones
that would be durable to any range of temperature, such as might be
used for cast-in-place.

I consider CNC to be okay because the human being with a saw or a
drill is God’s own CNC machine, even if precise to only 3
significant digits.

Thanks,
Andrew Jonathan Fine


#9

Museum conservation departments will have the that you
require especially the larger ones

Robin Key
Clavis Jewellery
Aberdeen, Scotland


#10
Which was one of the more popular mediums for Pietra Dura. For the
most part, these forms of intarsia were set on a base plate unlike
the backless intarsia that is commonly done today (a method that
only really became practical with the introduction of modern
adhesives). The more portable items were done on metal backing
plates. 

I work with Mammoth Ivory and the Backed Base Plate is actualy call
INTAGLIA, a word no longer found in the english language. I was
tought that it originated from China in the 13th century where the
art was used only for jewelry of the nobles and Jade, Gold and Ivory
were used.

This techneque used pins both threw the backing as well as
horizontaly threw each piece in the pattern. I do use CNC in my
Intaglia, but it is more of a security issue as Ivory like wood
exspands and contracts.

Sincerely LeeC
MammothIvoryCreations.com


#11

I actually stumbled completely by accident into the pietra dura shop
that John Donivan provided that link to. If ever you are in Florence
by all means go out of your way (not that anything in Florence is
really “out of the way”) to visit this shop. It is truly wonderful.

Catherine Galloway


#12
I work with Mammoth Ivory and the Backed Base Plate is actualy
call INTAGLIA, a word no longer found in the english language. 

Don’t know where you are getting your info? Intaglia is commonly
known among jewelers as a gem that has carving that goes below the
surface of the gem material. Google “definition intaglia”. Correct
definition and usage, not lost, not gone, not forgotten.

Richard Hart G.G.
Denver, Co.


#13
This techneque used pins both threw the backing as well as
horizontaly threw each piece in the pattern. I do use CNC in my
Intaglia, but it is more of a security issue as Ivory like wood
exspands and contracts. 

That makes sense. I’ve seen photos and a couple of museum exhibits of
jade pieces done that way, but couldn’t get a good enough view to see
assembly detail.

I haven’t tackled the mammoth ivory, but I have done a lot of bone,
and yes, you have to treat it like a very hard, but brittle wood.

I think that I need to dig into this in depth. I’ve been looking for
a new direction to try with my lapidary work. I have the basics down,
but I haven’t really found that “next step” that really appeals.

Ron Charlotte – Gainesville, FL


#14
I actually stumbled completely by accident into the pietra dura
shop that John Donivan provided that link to. If ever you are in
Florence by all means go out of your way (not that anything in
Florence is really "out of the way") to visit this shop. It is
truly wonderful. 

I will put it on the list. To celebrate the completion of her
Masters Degree (and a long delayed honeymoon) my wife and I are going
on one of the Smithsonian art tours of Venice, Florence and Rome this
coming spring, and we are making lists of stops for the non guided
days of the tour.

Ron Charlotte – Gainesville, FL


#15

Dear LeeC,

Your technique appears to be extremely interesting. I did some
surfing on intaglia and cannot find anything about it. To me it is
irrelevant as to whether your technique originated from China or even
from Atlantis (humor), but I would very much like to know more about
it. May I please contact you by email for advice?

Thanks,
Andrew Jonathan Fine


#16

Ron,

A pretty broad array of adhesives common in the 1400s can be found
in the _Craftsman's Handbook" by Cellini. 

Your description of ancient methods got me curious, and then that
Cellini had written a techniques book! So I searched to see if The
Craftsman’s Handbook was available in my county cooperative library,
and indeed it is, but written by Cennino Cennini.

So I googled Cennini and Cellini together and ultimately ended up on
the website of the Guttenberg Project (which, for any who don’t know
it, is one of the most amazing of web resourses) and was looking over
the Autobigraphy of Benvenuto Cellini. I did a word search in the
text of the autobiography for ‘Cennini,’ and came up with this
remark:

IT happened at this time Ottaviano de' Medici, who to all
appearances had got the government of everything in his own
hands, favoured the old master of the Mint against the Duke's
will. This man was called Bastiano Cennini, an artist of the
antiquated school, and of little skill in his craft. 

Of course, this is not the author of the book to which you refer,
but I thought the whole things was rather interesting. I read a few
bits of Cellini’s autobiography (which, like everything on the
Guttenberg site, is a free download)

Cheers to all, and thanks for the interesting conversations - Dale


#17
I think that I need to dig into this in depth. I've been looking
for a new direction to try with my lapidary work. 

Just FY (everyone) I… Some of the ways it is done, and can be
done. I’ll say right here I see no advantage to having CNC in almost
all cases, but if someone can find one, good for them…I’m going
to call everything “inlay” because this isn’t about words…

The simplest and easiest way is to make a space and fill it with
stone. That means making a square space in metal and cutting a stone
that fits into it, or making a 3x6 grid of squares and filling
those. They can be ground flush or they can be “buff-top” - each one
domed and cabbed on top. An extension of this is to make an
elaborate shape and fill that - I still have a pair of bluebird
inlays I did in mother of pearl: Grind a cab, sawpierce the design,
back it with some metal (aluminum…) and cut and fill the design
with stone. That’s a Dennis Edaakie thing, among others…

The next level is to make a canvas - like a bezel soldered on a
sheet, and fill that with design. I call this “mosaic”… That means
to cut a flower in the center and fill the whole space with flower
and background, all in stone. Sort of related to this is similar to
Venetian Glass beads - people built up strips and bits of stone and
glue them together, and then when they cut off the end they get a
little cab with the design built into it. Many American Indian
designs use this for production reasons - little “buttons” with
inlaid faces in them.

The thing about all of those is that they use grinding wheels, or
similar. Little bits and pieces of angular stone that are cut and
fitted together - curves can be done but they are tricky without
special wheels - Crystallite used to make a “full circle wheel” with
a radiused edge - I imagine they still do, or somebody, but maybe
not by that name…

Two hints: if you are cutting little pieces to fit into spaces, like
rectangular silver holes, it is better and easier to cut at a very
slight angle. If you are doing mosaic as I describe above, then you
should have square edges all around. And cut a bit, glue a bit and
clean up the glue before the next cutting.

True Pietra Dura mosaic is an entirely different animal. Art is
drawn and templates are made out of paper, which is glued to stone
slabs. Then those shapes are sawn out of the slab with a wire saw -
circles, arcs, curves, anything. Then those pieces are glued
together as-is, or virtually so. Very technical, very
time-consuming.

There is also micro-mosaic - in the Southwest it’s “chip-inlay”.
That’s little teeny-tiny squares or just bits of stone that are
simply arranged in shapes and glued down. That’s another issue
entirely…


#18

Ron

I think that I need to dig into this in depth. I've been looking
for a new direction to try with my lapidary work. I have the basics
down, but I haven't really found that "next step" that really
appeals 

I think this is the hint I actually needed… and it doesn’t need to
be done with an ivory backing… I’m thinking that optical quartz
backing with same material for pins would be ideal for my purposes.

We should talk.

Andrew Jonathan Fine


#19

The simplest and easiest way is to make a space and fill it with
stone. If you are using a bezel of couse it would be easier to start
at the center of the intarsia and work outwards, then make bezel to
fit. Much easier.

I have often thought about making grooves in the pieces that go in
the intarsia and using thin strips of metal to go into the grooves
and hold the pieces together (same idea as pins I guess). However,
intarsia is labor intensive enough without that extra step and it
isn’t really needed. If you angle each piece of the intarsia ever so
slightly so that as viewed from the side, the top of each piece is
slightly closer to the center of the intarsia, then it is 'locked’
in. Put another way, you grind the sides of each piece to be added to
the centerpiece of the intarsia, at a slight angle such that if you
tried to pull it straight out of the assembly (and assuming the edges
of hte intarsia are held firmly by the bezel) you could not. Of
course this does not completely negate the need for glue, but it does
add a measure of structural integrity. Even if you had a way to
structurally hold the piece together with need for glue, you might
still want to use it as it helps hide the seams between individual
pieces in hte intarsia. Especially CA glue, with takes a decent
polish. Incidentally the only thing I’ve EVER had come unglued was
mammoth ivory. It’s hard to imagine exactly how a well made intarsia
would ever come apart, assuming it wasn’t left in a swimming pool for
a week or somehting like that.

I guess that the epoxy could deteriourate over a long enough time.
There are high quality epoxies such as HXTAL that are ultra pure,
and if youmix them precisely (proportions) and mix thoroughly, will
last a very very long time. They take a week or so to cure though,
but might be worth the inconvenience.

Todd Welti
www.livingcoloropals.com


#20

Dear Andrew Jonathan Fine,

I would be honored to give you any advice you need on the art. You
can find a full discription of what I do and how I do it on:

http://www.MammothIvoryCreations.com look under Intaglia, also there
is a Galary of past works, that holds alot of my past Intaglia works
on the site as well. I think I have covered it here on the Ganoksin
Blog as well. http://leehulcher.ganoksin.com/blogs/

LeeC