Re: Gum hardening -- top down?

From: TERRYAKING@aol.com
Date: 04/05/06-08:40:43 AM Z
Message-id: <321.1a397f9.316530eb@aol.com>

The difficulty with many of Mike's 'speculations' or assertions is that one
simple test will disprove them. Try, for example what happens if you make a
platinum print with a 1.2. or 3% gelatine size.. No precipitation and no need
for Tween or special papers not sized with gelatine.

Anyone making carbon prints or gum prints will have conducted this test every
time they make a print. Experience is that the gum or gelatine hardens from
the top. That is why too short an exposure leads to the picture sliding off the
page; the gum has not hardened at the surface of the paper..

Stopping to think for one moment will demonstrate the truth of this. Sandy
has amply made the point by demonstrating that the gum hardens at the paper
surface when it is exposed from the back.

Terry

In a message dated 5/4/06 3:07:13 pm, kthayer@pacifier.com writes:

>
> In the past,  the "proof" that has been offered here for hardening at 
> the paper surface is no proof at all but Mike Ware's speculation that 
> the dichromate may be strongly absorbed  to the paper;  he thinks it  
> may move down through the layer  and congregate at the paper 
> surface,  and if this is  so,  that is where hardening would take 
> place, because that is where the bulk of the dichromate would be 
> found. 
>
Received on Wed Apr 5 08:41:07 2006

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