Concentrate - Stock - Working Strength?

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Dan Quinn - 24 Feb 2004 22:26 GMT

I know what working strength is. That is the solution strength
into which I place the film or print. But what are concentrate
and stock strength? Dan

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Gary Banuk - 24 Feb 2004 23:17 GMT

If you make up a stock solution of dektol you would make the powder up
to one gallon not put it into one gallon. Your working solution would
be when you take it out and dilute it to 1:1 as a working solution.

>I know what working strength is. That is the solution strength
>into which I place the film or print. But what are concentrate
>and stock strength? Dan

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Gregory W Blank - 25 Feb 2004 00:11 GMT

> I know what working strength is. That is the solution strength
> into which I place the film or print. But what are concentrate
> and stock strength? Dan

An example of concentrate HC110 syrup--- as it is purchased from
the photo store.

An example of HC110 Stock solution would be 1 part concentrate plus 3 parts water.

Working strength = whatever, but typical would be HC110 B dilution, 1 part stock plus 7 additional parts of
water.

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Bruce - 25 Feb 2004 00:11 GMT

Concentrate:
A liquid bought from the store to make a Stock Solution and reserved.

Stock:
The liquid or powder mixed into a "stock" solution to be further refined at
time of use. Usually the manufacturer suggests the amount of dilution.

Working Strength.
The Stock diluted to accomplish the desired results of development, stop, fix,
rinsing, toning. Often not following the manufacturers directions.

_________________
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Bruce
Brooklyn, N.Y.

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Jorge Omar - 25 Feb 2004 00:14 GMT

I think the best example is HC-110 as per Kodak's book:
Get the concentrate (as it comes in USA bottle) and dillute it 1+3 to
make the stock solution.
Then dillute stock for your working solution.

Do people REALLY do that?

Jorge

> I know what working strength is. That is the solution strength
> into which I place the film or print. But what are concentrate
> and stock strength? Dan

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Gregory W Blank - 25 Feb 2004 00:46 GMT

> Do people REALLY do that?

Why not ?

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Jorge Omar - 25 Feb 2004 01:23 GMT

Curiosity.
I've always used HC-110 straight from concentrate.

Jorge

Gregory W Blank <gblank@despamit.net> wrote in news:ffS_b.3419$Xv2.886
@nwrddc03.gnilink.net:

>> Do people REALLY do that?
>
> Why not ?

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David Nebenzahl - 25 Feb 2004 07:46 GMT

On 2/24/2004 5:23 PM Jorge Omar spake thus:

> Gregory W Blank <gblank@despamit.net> wrote in news:ffS_b.3419$Xv2.886
> @nwrddc03.gnilink.net:
[quoted text clipped - 5 lines]
> Curiosity.
> I've always used HC-110 straight from concentrate.

Same here: I don't see why anyone would *want* to mix stock solution from
HC-110. More work, and it goes bad faster. The only real problem with the
alternative (mixing working solution straight from concentrate) is having to
measure small quantities, and that's easily solved with either a simple
syringe or a small graduate.

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Gregory W Blank - 25 Feb 2004 13:12 GMT

> Same here: I don't see why anyone would *want* to mix stock solution from
> HC-110. More work, and it goes bad faster. The only real problem with the
> alternative (mixing working solution straight from concentrate) is having to
> measure small quantities, and that's easily solved with either a simple
> syringe or a small graduate.

*Unless* you only mix enough stock to make the required amount
for a batch or two of film. That way you can use a simple cough syrup
1 oz graduate, and there is no futzing around with guessing the increment
of concentrate.

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Richard Knoppow - 09 Mar 2004 22:06 GMT

> On 2/24/2004 5:23 PM Jorge Omar spake thus:
>
[quoted text clipped - 13 lines]
> measure small quantities, and that's easily solved with either a simple
> syringe or a small graduate.

For highly concentrated developers its sometimes easier to
measure accurately if a stock solution of intermediate
strength is made up. Generally, the more concentrate the
stock the longer it will last. A diluted stock solution of
Rodinal is probably not practical because it would oxidize
pretty quickly but HC-110 is more resistant. The concentrate
will still outlast any dilution.

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