[pure-silver] Re: Perceptol
- From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 16 May 2005 16:42:31 -0400
According to the msds, Perceptol contains a large amount of sodium
bromide 10 - 30% in part B. No mention of sodium chloride. The sodium
bromide may act the same as the sodium chloride in Microdol-X or it may
not.
Jerry
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Richard Knoppow
Sent: Monday, May 16, 2005 4:29 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: Perceptol
----- Original Message -----=20
From: "Justin F. Knotzke" <jknotzke@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Monday, May 16, 2005 8:15 AM
Subject: [pure-silver] Re: Perceptol
> On 5/15/05, Richard Knoppow <dickburk@xxxxxxxxxxxxx>
> wrote:
>>=3D20
>> FWIW Kodak Microdol-X is identical.
>
> Ahh thanks, I didn't know that.
>
> Anyone know how they compare to XTOL with FP4 ?
>
> J
>
>
> --=3D20
> Justin F. Knotzke
> jknotzke@xxxxxxxxx
> http://www.shampoo.ca
>
FP4 is a film, is there also a developer?
Microdol-X and Perceptol are extra-fine-grain developers=20
which employ sodium chloride (plain salt) as the fine grain=20
agent. When used full strength they loose about 3/4 stop of=20
speed by deliver noticeably finer grain than most other=20
developers. When diluted they loose the extra-fine-grain=20
property but deliver normal (i.e. D-76) speed. At 1:3 they=20
become "acutance" developers. Both employ Metol as the=20
exclusive developing agent. For a time the MSDS for=20
Perceptol was in error, showing sodium bromide rather than=20
sodium chloride but its fixed now. There may be small=20
variations in the two commercial products. AFAIK, there has=20
never been a published formula for this type of developer=20
although there are some pretty good guesses.
Xtol is a new developer employing a form of Phenidone and=20
Ascorbic acid as the developing agents. It was designed to=20
be environmentally friendly and to be easily mixable from=20
powders in room temperature water. It is successful in the=20
first item, maybe not so much in the second.
Xtol has excellent properties as a developer: it has=20
finer grain and higher speed than D-76 and good sharpness=20
qualities. Its downfall is occasional and unpredictable=20
sudden failure. The cause of this problem is not fully=20
known. A freshly mixed batch of developer may work perfectly=20
and develop only weakly a few days later. Many people have=20
never had this problem but I've had it with a five liter=20
package of Xtol mixed maybe six months ago. Within three=20
weeks it began to develop very weakly. I contacted Kodak.=20
They sent me a replacement package very promptly but claimed=20
the problem doesn't exist. Well, I've read enough posts on=20
usenet and on various mailing lists to know that it does=20
exist and is not too rare. This is too bad because otherwise=20
Xtol is an ideal developer.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx=20
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