From: Gordon J. Holtslander (holtsg@duke.usask.ca)
Date: 07/11/03-12:57:59 AM Z
On Thu, 10 Jul 2003, Katharine Thayer wrote:
> Gordon J. Holtslander wrote:
> >
>
> >
> > Is gum viscosity significant in gum printing?
> > Does viscosity influence gums hardening with a dichromate?
>
> I think so; isn't that why instructions for gum printing generally
> specify gum with a specific gravity of 14 Baume? I've always assumed
> that specific gravity is related to viscosity, no?
>
I was curious so I checked this. According to this reference
(http://www.csgnetwork.com/sgvisc.html) There is no correlation between
specific gravity and viscosity.
specific gravity is a measure of the density of a substance compared to
water.
viscosity is a measure of a liquids resistance to flow.
The two are different.
Denser liquids are often more viscous, but if the above is correct liquids
with the same specific gravity could have different viscosities.
It may be possible to alter the viscosity of gum arabic by changing its
pH. Does its specific gravity change? Does it matter in gum printing?
(I sound like my seven year old daughter asking too many quesions :) )
Gord
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Gordon J. Holtslander Dept. of Biology
holtsg@duke.usask.ca 112 Science Place
http://duke.usask.ca/~holtsg University of Saskatchewan
Tel (306) 966-4433 Saskatoon, Saskatchewan
Fax (306) 966-4461 Canada S7N 5E2
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