From: Jeffrey D. Mathias (jeffrey.d.mathias@worldnet.att.net)
Date: 06/21/00-05:30:04 AM Z
Nick Makris wrote:
> ...
> Jeffrey, are you saying that the one drop method will produce similar
> contrast adjustment through the use of a lesser concentration than that
> which is used in the two solution method???
NO. Contrast is related to the concentration of the contrast agent in
the coating solution independent of whatever method of mixing the
coating solution is used.
>
> I'm only trying to understand how the chemistry is different - we all seem
> to agree that the answer to the quiz is something just greater 16%.
> However, you are saying that a solution of .5%-2% will effectively render
> the same contrast adjustment ...
NO AGAIN.
What I said is that I typically would use 0.5% to 2% PC for an 8x10, if
I wanted to increase contrast a bit. HIGHER AMOUNTS WILL DEGRADE THE
IMAGE.
> ... and therefore the effective equivalent
> concentration (using a 1% norm) is 1/16 of .33%.
There is no "effective equivalent". HIGHER AMOUNTS WILL DEGRADE THE
IMAGE.
You are almost correct in that the "safe" amount should be less than
0.08% concentration in the total amount of coating solution when using
Bienfang 360. This concentration (0.08%) is achieved by mixing one drop
of a 2% PC solution plus 12 drops sensitizer solution plus 12 drops
metal solution.
-- Jeffrey D. Mathias http://home.att.net/~jeffrey.d.mathias/
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