[pure-silver] Re: 'Ripening' procedure for developer?
- From: "Jeffery Smith" <jls@xxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Fri, 4 May 2007 20:52:32 -0500
Then it is probably a good alternative to the borax. At least it's worth a
try.
Jeffery Smith
New Orleans, LA
http://www.400tx.com
http://400tx.blogspot.com/
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of mail1
Sent: Friday, May 04, 2007 8:03 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: 'Ripening' procedure for developer?
When Borax [Na2B4O7.(10)H2O] + Sodium Hydroxide [(2)NaOH] are fused together
sodium metaborate [(2)Na2B2O4.(4)H2O+(3)H2O]is formed Kodalk has alkaline
properties between those of Borax and sodium carbonate. Borax at 2% solution
yields pH 9.4 and Sodium Metaborate at 2% yields pH 10.4 Sodium Hydroxide is
very caustic alkali at pH 13
Jonathan Ayers [mail1@xxxxxxxxxxxxxxxxx]
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Jeffery Smith
Sent: Friday, May 04, 2007 2:22 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: 'Ripening' procedure for developer?
Well, this was a circular search. I had heard that some people used Kodalk
instead of borax. I went to PF, which states the following: "Kodak has
changed the name Kodalk; to Balanced Alkali; - this is their proprietary
name for sodium metaborate."
Inasmuch as sodium metaborate is borax, I'm glad I didn't order Kodalk.
Richard, do you know of other alkaline activators for the developer?
Jeffery Smith
New Orleans, LA
http://www.400tx.com
http://400tx.blogspot.com/
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Richard Knoppow
Sent: Friday, May 04, 2007 4:02 AM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: 'Ripening' procedure for developer?
----- Original Message -----
From: "Jeffery Smith" <jls@xxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Thursday, May 03, 2007 6:29 PM
Subject: [pure-silver] Re: 'Ripening' procedure for
developer?
Developers like D76 change for the worse over time. One of
the problems is
pH change, which affects the activity of the developing
agent. I have been
using divided D76, which is a bit more stable. The first
bath allows
inactive developer to soak into the emulsion. Time and temp
aren't
important. Transferred to the alkaline bath (borax), the
developer in the
gelatin becomes active until it is exhausted. The first bath
can be reused
over and over. The 2nd bath (cheap) is discarded.
But I am getting to the point that I don't trust developer
unless it is
fresh. I have bought about 5 kits of Paterson citric acid
developer. By the
time it reaches the states and gets into my darkroom, it is
DOA.
Jeffery Smith
New Orleans, LA
http://www.400tx.com
http://400tx.blogspot.com/
D-76 is an interesting case. Shortly after the formula
was released in 1927 it was discovered that its activity
increased slowly. The real cause took decades to discover
but the immediate cause was a rise in pH. In 1929 a research
paper was published by Kodak Research Labs describing the
problem and a solution for it along with data on a great
many variations of the formula. The cure was to buffer the
solution by using a combination of Borax and Boric acid. The
data in the paper shows the the developement time for the
original formula for a given gamma was reduced to a bit more
than half the time after storage for about a month. For the
buffered version there was insignificant change over the
same period.
It was discovered much later that the mechanism for the
pH rise was a slow reaction between the Hydroquinone and the
Sulfite which produces a small amount of Sodium Hydroxide.
Developers which do not contain Hydroquinone do not suffer
from this problem. It is likely that the pH of many M-H
developers are high enough to begin with that the small rise
from this reaction is of no significance.
The packaged version of D-76 has been the buffered type
for several decades. For those interested the formulas are
as foll
Standard D-76
Water (at 125F or 52C) 760.0 ml
Metol 2.0 grams
Sodium Sulfite, dessicated 100.0 grams
Hydroquinone 5.0 grams
Borax 2.0 grams
Water to make 1.0 liter
D-76d
Water (at 125F or 52C) 750.0 ml
Metol 2.0 grams
Sodium Sulfite, dessicated 100.0 grams
Hydroquinone 5.0 grams
Borax 8.0 grams
Boric Acid, Crystaline 8.0 grams
Water to make 1.0 liter
This will have the same activity as the original formula
when fresh.
The activity of the buffered developer can be varied over a
wide range by changing the relative amounts of Borax and
Boric Acid.
Crystaline Boric Acid should be used because the granulated
variety dissolves with great difficulty.
A note about packaged Kodak products: Kodak has a
large number of patents for the stabilization of the
ingredients of both powder and liquid developers and other
chemistry. They also seem to have paid a lot of attention
over the years to sequestering agents, etc., to make their
packaged chemistry as nearly immune to water quality as
possible. No doubt other manufacturers have done the same.
Other than a couple of bad experiences with Xtol I have
never had a failure with any packaged Kodak product. There
is a limit of lifetime to the materials in the paper
packets. The packages are made of a paper lined with
metalized plastic. They were supposed to be completely
impervious to air and moisture but obviously are not. I
don't know the mechanism of the failure but suspect it is
micro-cracks in the metalized plastic liner. In any case,
I've opened very old packages of Dektol which looked like
coffee grounds and smelled like dead mice. Not nice. The
very old stuff in hermetically sealed tin cans seems to last
forever. A couple of years ago Kodak got rid of the paper
packages in favor of all plastic ones with one less seal.
Its too soon to know how well these hold up for long time
periods.
Some liquid concentrates do not have unlimited life.
For instance, rapid fixer will eventually decompose. Again,
I don't know the mechanism but it may be due to leakage of
air through the plastic containers and is at least partly
due to the inherent instability of the chemicals although
they are treated to improve their stability.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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