[pure-silver] Re: D-76 and variations

Gerald

Is that why I see no rise in activity in ID-11 if I seal it from air
completely?





Regards



Ralph W. Lambrecht

http://www.darkroomagic.com







On 2005-11-28 19:04, "Koch, Gerald" <gkoch02@xxxxxxxxxx> wrote:

> 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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