Re: gum arabic
Sorry, I should have all of the thread before I asked the question. On Thu, Jan 29, 2009 at 7:57 AM, Keith Gerling <keith.gerling@gmail.com> wrote: > Can anyone explain what a user might notice if she was using a poorer > quality gum? In the experience of the users, how does the pedigree pf > the gum affect the print or the process of printing? > > On Sat, Jan 17, 2009 at 11:56 AM, Katharine Thayer <kthayer@pacifier.com> wrote: >> P.S. The term "gum arabic" is used rather loosely, sometimes to refer to >> acacia senegal, sometimes to gum acacia of any variety, and sometimes even >> to other species, so I wouldn't put too much faith in the term "gum arabic" >> as being synonymous with acacia senegal. >> kt >> >> >> >> On Jan 17, 2009, at 9:18 AM, Alberto Novo wrote: >> >>>> Also, sort is important; the kordofan, labeled (1) will be a higher >>>> (finer) sort than the other, at sort 3. Hope that's helpful, >>>> Katharine >>>> >>> >>> As for Kremer's gum arabic, their pdf on their gum details is the same for >>> the three qualities, though their prices are different, so I am wondering >>> what they really are. I am not buying from Kremer, because I have about 1 kg >>> of gum arabic of unknown origin since a long time (though it works well). >>> About Acacia senegal (cited from Kremer pdf): >>> "Gum Arabic is a dried exudate obtained from the stems and branches of >>> Acacia senegal (L.) Willdenow or closely related species of Acacia (fam. >>> Leguminosae). A. seyal is a closely related species. Gum arabic consists >>> mainly of high-molecular weight polysaccharides and their calcium, >>> magnesium, and potassium salts, which on hydrolysis yield arabinose, >>> galactose, rhamnose, and glucuronic acid. Items of commerce may contain >>> extraneous materials such as sand and pieces of bark which must be removed >>> before use in food. Gum arabic from A. seyal is sometimes referred to as gum >>> talha." >>> "Gum Arabic from A. senegal is a pale white to orange-brown solid, which >>> breaks with a glassy fracture. The best grades are in the form of whole, >>> spheroidal tears of varying size with a matte surface texture. When ground, >>> the pieces are paler and have a glassy appearance. Gum from other acacia >>> species may not have the characteristic tear shape and are often darker in >>> colour. Gum from A. seyal is more brittle than the hard tears of A. >>> senegal." >>> One among the differencies (not easily testable at home) is their optical >>> properties: water solutions from A. senegal are levorotatory, from A. are >>> dextrorotatory. >>> Alberto >>> >>> >> >> >
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