TERRYAKING@aol.com wrote:
> specific gravity is a factor in the expression of viscocity even in industrial
> measuring devices
Don't keep things too simple...
Viscosity is due to the action of internal forces among the molecules, while
density is simply the ratio weight/volume. For most of the organic
substances viscosity is related to the molecular weight.
The empirical relation between density and viscosity is valid for each
substance, so that in an industrial process where the same substance may be
more or less diluted, density may be used instead of viscosity.
> We were told that one should choose aq PVA which corrsponds best to 14 Baume.
> In fact one can vary the specific gravity ( Baume is a scale of specific
> gravities of heavy liqids) by varying the amount of water..
In my opinion one should dilute his PVA until it feels like his gum when
brushing. That is, viscosity (and not density) is more or less the same.
As for PVA and gum arabic print definition, I would suggest to consider in
this group also caseine and egg (temperaprint) prints. I never tried, but I
think that also a starch glue should work...
Alberto
Received on Tue Apr 4 08:17:29 2006
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