Re: gum, powdered pigments and powdered arabic

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From: Christina Z. Anderson (zphoto@montana.net)
Date: 04/17/03-06:05:12 PM Z


<Judy said>
> If you're getting a "light amber" gum from D. Smith, you may be buying
> their "premium" gum, not their "lithographer's gum," which in any event
> varies from year to year, and, being quite dark is almost certainly not
> made by them from powder.
> I gather their product line and pricing have changed. It's possible they
> only sell one gum now -- but when I last bought a gallon of Daniel Smith
> "lithographer's gum" for $16 it was quite dark--- and WONDERFUL. In fact
> I suspect that something in the dark is good --it certainly worked much
> better than the lighter "premium" I bought from them at the same time for
> four or five times the price.

     When did you last buy gum from D. Smith? It's $43 a gallon now for
that
type (!).
     I checked with them--yes, the powder I have is premium light amber.
And
yes, they do mix their own liquid gum up from this very powder. So save
yourself some bucks and buy powder... for half a pound which mixes up to
about 4/5 liter, it is $12. For 1/2 a liter of liquid it is $13.50. Maybe
the inconvenience of mixing powder isn't worth the savings, but it is
cheaper than the gallon price.

> However any of those prepared gums has a preservative, which the gum you
> mixed up presumably doesn't. There has been some claim that when the gum
> goes sour it doesn't work -- that seems not to be true. In fact some
> printers have said they PREFER the sour gum. However it does continually
> change, lacking preservative -- so it would tend to work quite differently
> over time. That is, your ratios/color effects, etc, would most likely
> change.
> There's also the matter of odor.... which some claim can get quite
> intense as the gum sours.

> Judy
I'll be watching and smelling to see how long it takes to sour. Some of the
powdered pigments (ultra blue and cadmiums) smell bad enough as it is ...but
I have a super sensitive nose.
Chris


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