U of S | Mailing List Archive | alt-photo-process-l | Bleach Development with Gum

Bleach Development with Gum

Chris and All,
                         John ( thats me )  is not a professional chemist.
But, I know someone who is ; Alberto Novo, who may be able to unravel what
you were reading on the link you give.

Re my experience of solutions of  Sodium Hypochlorite which I have mentioned
several times over the last few postings, they seem fairly meagre when
reading the way Marek has reached an almost predictable way of using the

The struggle to get my prints on the Picasa w/s to show how clever I am
 has occupied a couple of hours and left me exhausted and in need of high
protein sustenance.

 NOTE  ''I'' before ''E''  except after ''C'' defies the rule in this case.
.....the same as  ''LEISURE''

See you later if I can recover

                   Maybe, some pics, soon.

Ciao. John - Photographist - London- UK

----- Original Message -----
From: <
To: <
Sent: Monday, December 03, 2007 4:30 PM
Subject: Re: Bleach-development with gum recipe

> Marek or John,
> You are chemists, correct?
> Well, when I check online here:
> There is an interesting discussion of mixing a 0.5% bleach.
> Anyway, it talks of mixing a bleach with a powder, and to
> get a 0.5% it is like 7g of powdered calcium hypochlorite,
> etc. etc.  and that these powders are "chlorine releasing",
> hence the discrepancy between a 7g/1000ml solution and the
> percentage--in other words powders do not provide a "pure
> bleach" gram per gram. Because I can't figure out how a 7g.
> per liter makes a .5% bleach solution...
> I guarantee I am saying this wrong, but I bet you'll
> understand and explain this to me?
> I don't know if sodium hypochlorite or potassium are the
> same way as calcium, but this would explain to me the
> discrepancy between the recipe for Eau de Javel/Javelle
> at 8g per 500ml from 1943 and
> this 5% thing.
> Do you know any chemistry info on bleach powders you could
> tell to shed light on this?
> The reason I ask, is I think it may be important, then, if
> this is the case--that powders provide less actual bleach
> than, say, Chlorox does, to make sure to match the liquid
> amount used to the original formula.  At the very least it
> may explain why you, John, use a much more dilute form of
> bleach than the recipe suggests, and Chlorox may contain
> many more grams of powder than its "5%" suggests. In any
> case, if there were an actual exact amount of modern day
> liquid bleach to equate with the old powdered formula would
> be comparing apples to apples.
> John, do you have an old recipe from back then of how much
> proprietary liquid Javelle water would have been used in a
> liter? It  seems that the concentration of it was 5% at that
> time.
> I don't know which form of hypochlorite was used,
> though...but in the same article I think it says the sodium
> form is 60% chlorine.
> Chris