[pure-silver] Re: D-76 and variations
- From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 28 Nov 2005 13:04:18 -0500
The problem with the rise in pH of D-76 with time is due to the
oxidation of hydroquinone. This is a fairly complex reaction in which
OH- ions are produced. It has nothing to due with either carbonates or
borax.
-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of John Black
Sent: Monday, November 28, 2005 12:51 PM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: D-76 and variations
>
>
> The original D-76 formula and Ilford's published formula for ID-11
> are:
>
> Water (at 125F or 52C) 750.0 ml
> Metol 2.0 grams
> Sodium Sulfite, dessicated 100.0 grams
> Hydroquinone 5.0 grams
> Borax, granulated 2.0 grams
> Water to make 1.0 liter
>
Seems like I remember the OLD original prewar formula for D76 was
accelerated with Na Carbonate and had a problem with increasing activity
with aging in solution that was traced to a rise in pH mediated by the
carbonate. All of which was remedied by switching to borate
accelerators/buffers. Am I dreaming or was that the case many years
ago?
JB
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