From: Loris Medici ^lt;[email protected]>
Date: 10/20/05-04:19:21 AM Z
Message-id: <000401c5d55f$bf9d1780$f402500a@altinyildiz.boyner>

My experience also is the same. Don't know what happens when you don't
filter the solution, though... Because I always filter the precipitate
which is formed when mixing the sensitizer (filter a second time one or
two days later, no precipitation after that - much less compared to the
first time - only silver plating but maybe 10-12 months later, I usually
use up the sensitizer before that - silver plating - occurs).


-----Original Message-----
From: Judy Seigel []
Sent: 19 Ekim 2005 Çarşamba 09:45
Subject: RE: VDB

On Mon, 17 Oct 2005, Fabiano Busdraghi wrote:
> the only things I don't like is the precipitate that forms in the
> bottle. I adds solution C really slowly (30' to add 33ml of c solution

> to 66 of a+b). after more or less 25ml the solution start to
> precipitate. I wait two days and then I filter all this green
> precipitate. the solution is light green, and if I don't filter it I
> have I grainy and inconsistent result. I don't like the precipitate
> cause I say to my self that I'm loosing some salt that could be used
> to increase dmax...

I've puzzled over this report, Fabiano, and -- aside from awe at your
precision (makes me feel like Jackson Pollack) -- I can only suppose VDB

is something like gum, in that there are MORE VARIABLES than we know.

I admit I never measured VDB emulsion -- had it in an 8 ounce (ca 250
ml) dropper bottle and would drop the contents of 2 or 3 or however many

of the looong droppers at the edge of the paper and spread with a damp
foam brush. Still, I would have noticed graininess... And it was months
before a precipitate was visible in the bottle. Maybe the chemicals are
different here & there? (I always used tech grade.) Or the distilled

Or the air?

Received on Thu Oct 20 04:15:35 2005

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