[pure-silver] Re: One package chemicals
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Wed, 15 Dec 2004 21:08:32 -0800
----- Original Message -----
From: "DarkroomMagic" <info@xxxxxxxxxxxxxxxx>
To: "PureSilverNew" <pure-silver@xxxxxxxxxxxxx>
Sent: Wednesday, December 15, 2004 4:52 PM
Subject: [pure-silver] Re: One package chemicals
>I heard Kodak will replace oxidized bags of Dektol. I had
>one once and
> tested the brown vs light new Dektol. The new Dektol had a
> higher Dmax than
> the oxidized version. I discarded the oxidized Dektol.
>
> BTW, I still have very old Dektol in tin cans. So far,
> they have all been
> fine and show no signs of color change.
>
>
>
>
>
> Regards
>
>
>
> Ralph W. Lambrecht
>
>
>
The bags Kodak has used until recently are paper coated
with metalized plastic. They were intended to provide the
same protection from oxidation that the hermetically sealed
cans of yore did but are nowhere near as good. My personal
guess is that the coating developed micro-cracks which over
time let in enough air to oxidize the powders. Kodak has now
changed to a plastic material and also to a form where one
seam is eliminated.
I've had Dektol I bought go bad after a few years. For
normal storage times, i.e., a few weeks or months, the bags
were fine. For long term storage they are a disaster. I once
bought some old Dektol at a local sale. I don't know how old
it was but payed almost nothting for it. This stuff came out
looking like coffee grounds and smelling of phenol or old
fish, anyway, pretty awful. It went into the trash. Dektol
should be white. It mixes to a light amber color, which is
normal. I don't know what causes this. I haven't mixed
Dektol (D-72) from scratch for years so I don't remember
whether it was the same amber color or clear.
The change in Kodak packaging from cans to bags was
obviously done for reasons of economy. I guess they thought
the two were equivalent but it may be another case of "good
enough is OK". Most of the time packaged chemicals are used
pretty soon after manufacture so the "good enough" packaging
_is_ good enough. I guess this is closer to the ideal but I
still like the over-engineered stuff of the past.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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