U of S | Mailing List Archive | alt-photo-process-l | Re: daniel smith gum

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