Re: Tissue Problem

Eric Scott wrote:

> Hello -
>
> I've been making my own tissue for several months. I've had the usual
> problems associated with learning to make tissue, but have solved
> them. However, just recently I have had a new problem crop up that I
> have no idea what the cause is. My prints have a "swirl" pattern
> overlaid on the image. When I made another batch of tissue, I noticed
> that when the gelatin was "cooking", there was what appeared to be a
> "oil slick" on the surface, that was similar in pattern to what is on
> the print. This was just gelatin; I had not added sugar or pigment at
> that point. The drying tissue also has that pattern when viewed at a
> glare angle. So I see that the pattern is transferred to the print.
>
> The only thing I've done differently was to have the gelatin a
> container that is placed in a water bath on the stove. Previously I
> would put the container in a tray of hot water that I periodically
> added hot water to in order to maintain the temperature. I'm going to
> go back to that method to see if the problem goes away, but I'm
> wondering if anyone has any ideas.
>

I'd bet that if you examine the marked surface with sufficient
magnification, you'll see the marks take the form of microbubbles,
probably a mix of complete bubbles and the craters forms by bubbles that
burst after the gelatin is too hard to smooth out. The more rapid
heating with direct double boiler rather than your previous tray may be
affecting entrainment of air during dissolution of the gelatin, which
would otherwise manage to surface and the bubbles burst before the
gelatin is too stiff.

Of course, it's also possible that using the stove is introducing actual
oil (as smoke coming off the burner) if the same stove is also used for
food preparation.

-- 
After you use everything you know and can find out to make what you're 
certain is the right decision, and it's too late to change things or 
back out -- you'll find out something that would have reversed the whole 
thing for you, if you'd only known in time.
Donald Qualls, aka The Silent Observer   http://silent1.home.netcom.com
Opinions expressed are my own -- take them for what they're worth
and don't expect them to be perfect.
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