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
stuff.
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: <zphoto@montana.net>
To: <alt-photo-process-l@usask.ca>
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:
> http://www.reproline.jhu.edu/English/4morerh/4ip/IP_manual/10_Decontamination.pdf
>
> 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
>
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