Re: daniel smith gum
mary,
a while back i got completely confused about it and had to ask about it
on apug.
it might not be super-accurate, but it's easy and repeatable. i think
one has to add the weight of the gum into the calculation. then you get
a 300gr total - the gum being one third of it.
usually you mix the needed amount of a substance in less say 100ml and
the fill up. whith gum it's not so easy, because it takes a very long
time to dissolve the cunks.
acutally i get confused about the percent solutions all the time and
that's why i added the grams +ml to the text.
phritz
Mary Pat Mcnally schrieb:
I don't understand how you arrive at a 33% solution of gum if you
dissolve 100 gr of gum in 200 ml of water.
Mary Pat
On Sep 29, 2009, at 4:10 PM, phritz phantom wrote:
paul,
i use chunks of gum instead of the powdered, but the amounts should
be the same. it only takes longer to dissolve.
i make a 33% stock solution ( 100gr gum + 200ml of distilled water)
and i dilute it 1+1 for use (a ~16% solution). because i found that
the 33% solution gets sticky too quickly when painting on the
emulision. it starts drying, before i can even it out.
i don't use any preservative at all, but i keep the gum solution in
the fridge. this way it keeps at least for a few months (even when
not using distilled water, which i once did).
best wishes
phritz
Paul Viapiano schrieb:
Katharine...thanks, and btw...if I buy some DS powdered gum, how
should I mix it?
p
----- Original Message ----- From: "Katharine Thayer"
<kthayer@pacifier.com>
To: <alt-photo-process-l@usask.ca>
Sent: Tuesday, September 29, 2009 12:01 PM
Subject: Re: daniel smith gum
I looked up that previous discussion about how some gum arabic is
not acacia senegal but acacia seyal. It was a link to a Kremer
page supplied by Alberto Novo in January of this year that
alerted me to the difference between acacia senegal and acacia
seyal, the description of the brittleness of the dried acacia
seyal making me wonder if perhaps the Daniel Smith premium gum may
be at least partly acacia seyal.. I can't seem to find my way
back to the exact Kremer page to link it directly, but here's a
post where Alberto copied the relevant paragraph from the page:
http://www.usask.ca/lists/alt-photo-process-l/200901/msg00118.html
The fact that the Kremer price list at that time identified at
least one of their gum arabics as a mixture of acacia senegal and
acacia seyal, made me wonder even more whether Daniel Smith may
also mix these two types of acacia, but was unable to get an
answer to my question from Daniel Smith. Now the Kremer price
list specifies that their powdered gum arabic is either acacia
senegal OR acacia seyal, no way of knowing which one you're going
to get.
The Daniel Smith premium gum does print very nicely, don't get me
wrong, that's why I've kept with it in spite of my issues with
some of its qualities, but it does have these odd qualities.
My suspicion that it may be at least partly if not wholly acacia
seyal instead of acacia senegal is just a speculation on my part,
since I couldn't get an answer from Daniel Smith, but it's
definitely not the same material as the other gums I've used. And
I don't really know whether the powdered gum will turn out to have
the same qualities as the liquid premium gum, but I'm hoping it
won't. It would be helpful if they were more fothcoming about what
gum(s) they are marketing under the product name "gum arabic."
Katharine
On Sep 27, 2009, at 9:45 PM, Katharine Thayer wrote:
Paul, like all answers in gum, "it depends"....
I don't care for the standard (dark) gum, mostly because I mix
pigment/gum mixes by eye and I need the color and darkness of the
gum not to obscure the color of the mixture. I also once
believed someone's assertion that the dark color of the darker
gums sullies the brightness of the colors in the finished
print, but when I tested that assertiont, it turned out not to be
so. But I did find that the darker gums,including the DS
standard gum, tended to print with fewer steps (more contrasty)
than the lighter gums.
I've been using the Daniel Smith premium gum exclusively for
three- four years now, and I have a couple of issues with it. The
pigment/ gum mixtures I make with it seem to quickly become more
viscous and before long, dry up altogether. This never happened
with the old Formulary gum; I have mixtures of little-used colors
made with it that I've had mixed for years and years, that are
just as fresh as the day I mixed them. Generally my mixes made
with this Daniel Smith premium gum are unusable within 6 months
or so. This is a problem.
The gum also has a different quality than what I consider
quality gum arabic, a brittleness that I saw when I brushed
out unpigmented gum on a piece of paper and let it dry. Normal
gum arabic, brushedout in a thin coat, dries smooth with a
slight gloss; the DS premium gum is brittle when dry, and cracks
or flakes (shatters, actually, is a better word to describe what
it looks like) into shiny bits like tiny pieces of cellophane
that no longer adhere to the paper. I've never seen this happen
with the pigment mixed in, only with the plain gum. I don't know
what this means, but a description I read somewhere of a slightly
different type of gum, (not acacia senegal but a different
variety) including that it's more brittle than acacia senegal,
for example, sounded so much like the behavior of this gum that
I began to suspect that this gum may be at least a mixture of
acacia senegal and this other type of gum. I don't remember the
particulars, like what variety of acacia this other gum is from,
but I do remember that I wrote a post or two about it at the
time, which should be found somewhere in the archives. I called
Daniel Smith and asked, but no one could (or would) tell me
anything. They make their own watercolor paint, and one might
suppose that the gum arabic that they sell would be the same as
the gum arabic that they use in their watercolor paint, and you
would think that the people who make the paint would be able to
answer that question, what variety of acacia their gum arabic
comes from, but maybe they consider it a trade secret or
something. At any rate, I've recently mixed up a batch of the
gum they sell as powder, and while I haven't actually printed
with it yet, just mixing it and working with it, feeling its
character, it *feels* more like "gum" to me. We'll see. I'm
really quite tired of having to toss out dried up cannisters of
mixed gum/igment; it's a huge waste of pigment.
As to the Formulary, I don't know what they're selling now. I
used to love their gum but when they started selling something
resembling crankcase oil for their premium gum, I bailed out and
haven't bought gum from them since. But since gum, like wine,
changes from season to season, an observation made some time back
is essentially useless now.
Katharine
On Sep 25, 2009, at 3:36 PM, Paul Viapiano wrote:
Daniel Smith gum...standard or premium light?
Is there a big difference between the two and is it much
different than the Formulary gum?
Just curious...
Paul
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