Paul Lewing on thu 4 dec 97
I ran across an odd little article in the paper yestrday about
possible US sanctions on Sudan. In the article it was mentioned that
an exception had been made for the export of Gum Arabic, of which 90%
of the worlds's supply comes from Sudan. Now, I use a small amount of
GA in my ceramic work (a very tiny part of the 26,000 tons Sudan
produces every year), and it got me wondering.
Does anyone know exactly what Gum Arabic is and how it's produced?
What is it made from, and why does it only come from Sudan? My wife
mentioned that you can no longer get Gum Tragacanth, either. Is this
for the same kind of political reasons, or have Tragacanths gone
extinct?
None of my books had any information on this, but I'm sure there is
someone out there on this list who knows. I'm convinced that someone
on this list knows the answer to any question you could pose.
It also got me to wondering about the status of cobalt mining in
Zaire. Oops, the Republic of Congo.
Paul Lewing, Seattle
Tom Buck on fri 5 dec 97
Paul:
Arabic gum / gum arabic is a natural compound that oozes out of
plant or tree, just like pine gum or rosin. It comes from the plant
"Acacia Senegal" and commercially is called "arabic" rather than acacia
gum. Perhaps with the changes occurring the Shahara Desert and Shahel
region to the south, the Acacia Senegal plant now responds favorably to
conditions in Sudan rather than elsewhere.
Tragacanth gum is a similar plant product that comes from several
countries in eastern Europe and the Mid-East (Iran) and its supply likely
is fully committed to commercial end-products especially foods like
ice-cream.
Tom Buck ) tel: 905-389-2339
& snailmail: 373 East 43rd St. Hamilton ON L8T 3E1 Canada
(westend Lake Ontario, province of Ontario, Canada).
Marcia Selsor on fri 5 dec 97
Paul,
I think gum arabic is used in some fine art printing process but I don't
remember just which process.
Paul Lewing wrote:
>
> ----------------------------Original message----------------------------
> I ran across an odd little article in the paper yestrday about
> possible US sanctions on Sudan. In the article it was mentioned that
> an exception had been made for the export of Gum Arabic, of which 90%
> of the worlds's supply comes from Sudan. Now, I use a small amount of
> GA in my ceramic work (a very tiny part of the 26,000 tons Sudan
> produces every year), and it got me wondering.
>
> Does anyone know exactly what Gum Arabic is and how it's produced?
> What is it made from, and why does it only come from Sudan? My wife
> mentioned that you can no longer get Gum Tragacanth, either. Is this
> for the same kind of political reasons, or have Tragacanths gone
> extinct?
>
> None of my books had any information on this, but I'm sure there is
> someone out there on this list who knows. I'm convinced that someone
> on this list knows the answer to any question you could pose.
>
> It also got me to wondering about the status of cobalt mining in
> Zaire. Oops, the Republic of Congo.
>
> Paul Lewing, Seattle
Carol Durnford on fri 5 dec 97
At 12:18 PM 12/4/97 EST, you wrote:
>----------------------------Original message----------------------------
>I ran across an odd little article in the paper yestrday about
>possible US sanctions on Sudan. In the article it was mentioned that
>an exception had been made for the export of Gum Arabic, of which 90%
>of the worlds's supply comes from Sudan. Now, I use a small amount of
>GA in my ceramic work (a very tiny part of the 26,000 tons Sudan
>produces every year), and it got me wondering.
>
>Does anyone know exactly what Gum Arabic is and how it's produced?
>What is it made from, and why does it only come from Sudan? My wife
>mentioned that you can no longer get Gum Tragacanth, either. Is this
>for the same kind of political reasons, or have Tragacanths gone
>extinct?
>
>None of my books had any information on this, but I'm sure there is
>someone out there on this list who knows. I'm convinced that someone
>on this list knows the answer to any question you could pose.
>
>It also got me to wondering about the status of cobalt mining in
>Zaire. Oops, the Republic of Congo.
>
>Paul Lewing, Seattle
>
>
Paul: Gum Arabic is produced (gathered) from tropical trees in Asia, Africa
and Australian. The best grades have always come from Africa. Graded by
whether it is clean, pale in color or darker. The Amber or pinkish brown
varieties are supposed to have greater adhesive strength. In africa the
gum is often from Senegal or the Kordofan district of Sudan. The Senegal
gum is less easily dissolved than the Sudan variety, but for watercolors,
gum Senegal is preferred and produces a superior balanced product. Note
that without a preservative, a gum solution will decompose.
The gum tragacanth comes from the species of Astragalus (sorry I do
not have my botany books here right now). It is a shrub native to Asia
Minor. Used largely for a binder in pastels Gum Karaya - a cheaper
substitute in industrial uses (including artist materials production) has
replaced the gum tragacanth. Info complements of Ralph Mayer's The
artist's manual of techniques and materials, 5th edition 1991.
Dave Durnford
Box 2145
Missoula, MT. 59806
Durnford@selway.umt.edu
marvin s flowerman on sat 6 dec 97
Paul:
Gum Arabic is an exudate of the Acacia tree, specifically the Acacia
Senegal in the Sudan. Wherever the tree is injured (i.e. the bark is
torn) the tree bleeds (exudes) and the gum forms in what are called
"tears" , more or less round pieces ranging in size from about 1/2" to
3". That gum is than hand sorted according to various requirements,
exported all over the world where it is processed either by powdering or
spray drying into commercially useful product.
Why Sudan? Those acacia Senegal trees are indigenous to the sub-Sahara
belt of Africa and so there is also gum from Senegal (in West Africa),
Chad (which borders the Sudan) and Niferia which is considered West
Africa but the quantities are much smaller and the qualities unreliable..
The ban youd have read about goes into effect with imports arriving on
and after yesterday, December 4th, but imports will be possible with the
granting of import licenses for which a number of leading dealers have
taken steps to apply. There is also a large quantity of Gum Arabic
already in the USA which dealers brought in anticipating this
development.
On Gum Tragacanth: The principal traditional source was Iran. The USA
bans all commerce with Iran and so no gum can legitimately come from
there. Turkey has some too and that has been reaching the USA.
Tragacanth is also an exudate gum coming from smaller trees and bushes.
For practical purposes, I would doubt that you would have any difficulty
obtaining what you require of gum arabic; it might be prudent to double
up on your purchases so that you have a reserve.
I hope this has been helpful. (I have been in the gum business all of my
working life; now I'm a potter.)
Good luck
Marvin Flowerman (marvpots@aol.com)
On Thu, 4 Dec 1997 12:18:24 EST Paul Lewing
writes:
>----------------------------Original
>message----------------------------
>I ran across an odd little article in the paper yestrday about
>possible US sanctions on Sudan. In the article it was mentioned that
>an exception had been made for the export of Gum Arabic, of which 90%
>of the worlds's supply comes from Sudan. Now, I use a small amount of
>GA in my ceramic work (a very tiny part of the 26,000 tons Sudan
>produces every year), and it got me wondering.
>
>Does anyone know exactly what Gum Arabic is and how it's produced?
>What is it made from, and why does it only come from Sudan? My wife
>mentioned that you can no longer get Gum Tragacanth, either. Is this
>for the same kind of political reasons, or have Tragacanths gone
>extinct?
>
>None of my books had any information on this, but I'm sure there is
>someone out there on this list who knows. I'm convinced that someone
>on this list knows the answer to any question you could pose.
>
>It also got me to wondering about the status of cobalt mining in
>Zaire. Oops, the Republic of Congo.
>
>Paul Lewing, Seattle
>
Stuart Altmann on sat 6 dec 97
Paul:
Gum arabic is the gum of any of several acacia trees, but particularly
Acacia senegal and A. arabica, of North Africa and the Arabian peninsula.
Like other plant gums, it consists primarily of polysaccharides, that is,
its molecules are strings of sugar molecules linked together into
long chains. Plant gums differ from plant resins in being water soluble.
Gum arabic is widely used in the manufacture of inks, paper, textiles,
pharmaceuticals, adhesives, and so on.
I have had chemical analyses made of five samples of the gum of another
African acacia, the oft-photographed and widespread fever tree. Sugar
content ranged from 60 to 80%. The gum is a favorite food of baboons, vervet
monkeys, bushbabies, Kori bustards, and probably many other animals. To
humans, this gum is almost tasteless, yet baboons (which I studied for
many years in Kenya) treat it like candy. The component sugars of this gum
are primarily d-galactose and d-arabinose. Nobody knows whether we, or the
baboons, can digest it.
From the tree's standpoint, the gum functions, as do our blood clot and
scab, to prevent invasion by parasites. The viscous gum oozes out of
wounds made by woodpeckers, beetles, rhinos, elephants, etc., thereby
blocking entrance of various wee beasties that would otherwise take
advantage of these openings.
Stuart Altmann
Dana Henson on sat 6 dec 97
I don't know exactly what gum arabic is, but I do know that it is used as a
binder for watercolor pigments. If anyone is looking for gum arabic I would
suggest a quality art supply source, such as Utrecht.
Dana Henson
Don Jones on sun 7 dec 97
>----------------------------Original message----------------------------
>Paul,
>I think gum arabic is used in some fine art printing process but I don't
>remember just which process.
>
>Paul Lewing wrote:
That would be lithography. It is used to etch and seal the natural
limestones for printing. Also it is used to seal and store them after use.
Don Jones
claysky@highfiber.com
:-) implied in all messages and replies
http://highfiber.com/~claysky
Carol Durnford on sun 7 dec 97
At 09:09 AM 12/5/97 EST, you wrote:
>----------------------------Original message----------------------------
>Paul,
>I think gum arabic is used in some fine art printing process but I don't
>remember just which process.
>.
Gum Arabic is used in Lithography on both metal plates and lithographic
stones. Sometimes it is used as a glue/size in making paper.
Dave Durnford
Pete Land on tue 9 dec 97
Paul Lewing wrote:
> Does anyone know exactly what Gum Arabic is and how it's produced?
> What is it made from, and why does it only come from Sudan?
well, i _think_ it also goes by the name gum acacia (acacia gum), and is
produced from the sap of acacia trees which grow in the sudan (and probably
elsewhere). a woman i work with is from kenya, and she is familiar with
them from *back home*...
pete land
Conrad Krebs on thu 2 jun 05
Hello,
I'm hoping that someone out there can set me straight on how to mix up gum
arabic so that I can avoid the gum/glaze mixture settling out as a gummy
gloppy mess in the bottom of the bucket.
Here's what I've been doing. I have been mixing powdered gum arabic (equal
to 1.25% of the weight of the dry glaze) in warm water. To facilitate the
gum going into solution I have been heating the gum/water mixture slightly
in a microwave. I heat the mixture, stir it vigorously, heat it again, stir
again, etc, until it is completely dissolved. Is heating bad?
And now that I have a gummy gloppy mess, any ideas on how I can savage the
situation. The g.g. mess will go back into solution with enough vigorous
stirring but then immediately begins to settle out again. I have been
advised to add a tiny amount of sodium silicate. Does this sound right?
Thanks to all,
Conrad
Adam Yungbluth on thu 2 jun 05
From my experience with Sodium Silicate it will only cause you to have more
settling problems and make make it hard to apply to your piece(s) because
defloculating is what it typically brings to the glaze/slip party.
As far as the gum solution I have not used them before, but if you are
looking for a suspension agent you might try bentonite or white bentonite(if
for a celadon) or you may simply have a high Sodium or Lithium glaze and
just need to flocculate with some Epsom Salt
laters
Adam
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Phil Davenport on thu 2 jun 05
Gum Arabic does come in liquid form and has a preservative. Try some
are supply stores.
Phil Davenport
Garland, TX
-----Original Message-----
From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On Behalf Of Conrad
Krebs
Sent: Thursday, June 02, 2005 8:57 AM
To: CLAYART@LSV.CERAMICS.ORG
Subject: gum arabic
Hello,
I'm hoping that someone out there can set me straight on how to mix up
gum
arabic so that I can avoid the gum/glaze mixture settling out as a gummy
gloppy mess in the bottom of the bucket.
Here's what I've been doing. I have been mixing powdered gum arabic
(equal
to 1.25% of the weight of the dry glaze) in warm water. To facilitate
the
gum going into solution I have been heating the gum/water mixture
slightly
in a microwave. I heat the mixture, stir it vigorously, heat it again,
stir
again, etc, until it is completely dissolved. Is heating bad?
And now that I have a gummy gloppy mess, any ideas on how I can savage
the
situation. The g.g. mess will go back into solution with enough vigorous
stirring but then immediately begins to settle out again. I have been
advised to add a tiny amount of sodium silicate. Does this sound right?
Thanks to all,
Conrad
________________________________________________________________________
______
Send postings to clayart@lsv.ceramics.org
You may look at the archives for the list or change your subscription
settings from http://www.ceramics.org/clayart/
Moderator of the list is Mel Jacobson who may be reached at
melpots@pclink.com.
Marcia Selsor on thu 2 jun 05
When i was doing crystalline glazes 35 years ago, I mixed the gum
arabic in water to dissolve it and them added that solution to the
glaze. I think I read that in either herbert Sanders book on Glazing
for Special Effects OR Kenny's book , The Complete book on
Potterymaking.
Marcia Selsor
On Jun 2, 2005, at 7:56 AM, Conrad Krebs wrote:
> Hello,
>
> I'm hoping that someone out there can set me straight on how to mix
> up gum
> arabic so that I can avoid the gum/glaze mixture settling out as a
> gummy
> gloppy mess in the bottom of the bucket.
>
> Here's what I've been doing. I have been mixing powdered gum arabic
> (equal
> to 1.25% of the weight of the dry glaze) in warm water. To
> facilitate the
> gum going into solution I have been heating the gum/water mixture
> slightly
> in a microwave. I heat the mixture, stir it vigorously, heat it
> again, stir
> again, etc, until it is completely dissolved. Is heating bad?
>
> And now that I have a gummy gloppy mess, any ideas on how I can
> savage the
> situation. The g.g. mess will go back into solution with enough
> vigorous
> stirring but then immediately begins to settle out again. I have been
> advised to add a tiny amount of sodium silicate. Does this sound
> right?
>
> Thanks to all,
>
> Conrad
>
> ______________________________________________________________________
> ________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be reached at
> melpots@pclink.com.
>
>
Jim Pendley on thu 2 jun 05
Hello All,
Having used Gum Arabic in science for many years
before retirement, let me say that all Gum Arabic is
not the same. Purity is a big issue for solubility.
A scientific or "medical" grade is tested for addition
of starches and presence of tannin, which can decrease
the solubility in water, leaving a "ropey, stringy,
gelatinous material. Generally the high grade GA is
almost colorless as a powder, the more yellow, yellow
brown it is, the more tannin. There are lab tests for
adulterants. I would second the post of using the
"artists liquid" GA, as for watercolors, It can't
be "goopy" as above, but it also might be too thin
to use in glazes for adhesion, as I have never used
it.
Has anyone tried using old fashioned mucilage
glue
that had the slit rubber top? ( still available??) It
usually contained a different gum, but with similar
properties of GA. It came rather thick and can be
diluted with water as I remember.
Jim
--- Phil Davenport
wrote:
> Gum Arabic does come in liquid form and has a
> preservative. Try some
> are supply stores.
>
> Phil Davenport
> Garland, TX
>
> -----Original Message-----
> From: Clayart [mailto:CLAYART@LSV.CERAMICS.ORG] On
> Behalf Of Conrad
> Krebs
> Sent: Thursday, June 02, 2005 8:57 AM
> To: CLAYART@LSV.CERAMICS.ORG
> Subject: gum arabic
>
> Hello,
>
> I'm hoping that someone out there can set me
> straight on how to mix up
> gum
> arabic so that I can avoid the gum/glaze mixture
> settling out as a gummy
> gloppy mess in the bottom of the bucket.
>
> Here's what I've been doing. I have been mixing
> powdered gum arabic
> (equal
> to 1.25% of the weight of the dry glaze) in warm
> water. To facilitate
> the
> gum going into solution I have been heating the
> gum/water mixture
> slightly
> in a microwave. I heat the mixture, stir it
> vigorously, heat it again,
> stir
> again, etc, until it is completely dissolved. Is
> heating bad?
>
> And now that I have a gummy gloppy mess, any ideas
> on how I can savage
> the
> situation. The g.g. mess will go back into solution
> with enough vigorous
> stirring but then immediately begins to settle out
> again. I have been
> advised to add a tiny amount of sodium silicate.
> Does this sound right?
>
> Thanks to all,
>
> Conrad
>
>
________________________________________________________________________
> ______
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change
> your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be
> reached at
> melpots@pclink.com.
>
>
______________________________________________________________________________
> Send postings to clayart@lsv.ceramics.org
>
> You may look at the archives for the list or change
> your subscription
> settings from http://www.ceramics.org/clayart/
>
> Moderator of the list is Mel Jacobson who may be
> reached at melpots@pclink.com.
>
>
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