From: Stuart W Melvin (swmelvin@earthlink.net)
Date: 07/27/03-08:58:17 AM Z
oooops......thanks for the info.
To be more scientific.....we all get the gist......How thick is the stuff
Sam?
corrections applied:
I'm wondering if you might be able to elaborate on the viscosity of the gum
solution you use. Have you ever measured it with a baume meter? <disregard
baume meter question. What
ratios of water to gum (solution or powder) do you prefer?. Is your
viscosity preference consistent or do you find you vary it for any reason?
How does your viscosity preference relate to your application technique? So
many question marks........I must admire your technique hey.
Thanks,
Stuart
-----Original Message-----
From: Clay [mailto:wcharmon@wt.net]
Sent: Sunday, July 27, 2003 8:18 AM
To: alt-photo-process-l@sask.usask.ca
Subject: Re: Dry Dichromate and Gum, was Re: News from APIS
Industrial viscometers are pretty pricey. But googling "viscosity
measurement" gives you a nifty science project link:
http://www.science-projects.com/Viscosity.htm
that makes me think that measuring relative viscosity would be pretty
simple. If one uses the same size tube and bead, then the time it takes
to sink would give an idea of relative viscosity between two fluids,
since gravity is (at least for the precision involved here) the same
everywhere. Maybe at the next gum printers summit, everyone can
standardize on a 1/2 inch diameter 20cm tube and Daisy BB pellet or
whatever. Then when someone asks about your coating viscosity, you can
just say "4 seconds". Nice and low tech.
Clay
On Sunday, July 27, 2003, at 01:57 AM, Katharine Thayer wrote:
> Stuart W Melvin wrote:
>>
>> Hey Sam,
>>
>> I'm wondering if you might be able to elaborate on the viscosity of
>> the gum
>> solution you use. Have you ever measured it with a baume meter?
>
> Sorry to jump in here, but just thought I'd interject the comment that
> you're making the same mistake I'd been making all my life until a
> couple of weeks ago, when Gordon enlightened me. A baume meter
> (hydrometer) measures specific gravity, not viscosity, and what's more,
> the two are not related to each other. This information came to me like
> the apple falling on Newton's head, and this is why I asked the other
> day the speculative question about differences in viscosities between
> gums. I don't know if any of us has the equipment to answer this
> question; if someone does I'd sure like to know about it.
> Katharine
>
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