[pure-silver] Re: Weird Film Issue - Part II
- From: Jean-David Beyer <jeandavid8@xxxxxxxxxxx>
- To: pure-silver@xxxxxxxxxxxxx
- Date: Thu, 10 May 2012 21:27:45 -0400
Richard Knoppow wrote:
> ----- Original Message ----- From: "Nicholas O. Lindan"
> <nolindan@xxxxxxxxxxxxx> To: <pure-silver@xxxxxxxxxxxxx> Sent:
> Thursday, May 10, 2012 10:24 AM Subject: [pure-silver] Re: Weird Film
> Issue - Part II
>
>
>> Photoflo 600 is the 'industrial' version. It has 3x the
>> concentration of Triton and uses ethylene glycol rather than
>> propylene. It will suds-up just like PF200.
>>
>> If there were to be an anti-foaming agent I'd lay odds it would be
>> good ole' Dimethylpolysiloxane.
>>
>> I add PF directly to a bottle of isopropyl alcohol. 13ml of PF600
>> to a quart of 70% isopropyl gives a stock that gets diluted 1:7 for
>> use (1oz per 35mm film reel).
>>
>>
>> Nicholas O. Lindan Cleveland Engineering Design, LLC Cleveland,
>> Ohio 44121
>>
> A little research shows that there is a considerable difference in
> the toxicity of propylene and ethylene glycol. Propylene glycol is
> relatively non-toxic and is used in food and cosmetic products. That
> may be why Kodak chose it for a product aimed mostly at home
> darkrooms. Ethylene glycol is moderately toxic, one article points
> out that is danger is from its sweet taste which may lead children to
> ingest it. Both are used as anti-freeze and as wetting agents and
> humectants. I don't know how to tell the relative effectiveness.
> Kodak chose the ethylene for the industrial form of Photo-Flo but the
> reason is obscure to me. Perhaps cost or effectiveness. Someone
> with more chemical knowledge than I can perhaps explain. The other
> ingredient of both kinds of Photo-Flo appears to be Triton-X 100, AKA
> a bunch of chemical names, a non-ionic surfactant. There are also
> several other products sold under the Triton-X name, see:
> http://www.dow.com/surfactants/products/octyl.htm
>
>
I have only a residue of knowledge from high school chemistry and a
little bit from chemistry 5.01 and 5.02. Namely not much.
I do know that propylene glycol costs more than ethylene glycol.
Ethylene glycol is used in automotive cooling systems to reduce freezing
point (and raise boiling point). In this use, the chances of
contaminating a home water supply is negligible.
The main use I know of for using propylene glycol is in home heating
systems using forced circulation of hot water. In such systems there is
an anti-backflow valve to keep water from the heating system from
getting back into the domestic water supply. The connection between the
two is to allow makeup water to be added to the system to replace
leakage. Since those valves can fail in time, the codes normally do not
allow toxic additives to be added to the boiler water. So ethylene
glycol is out, but propylene glycol is used as anti-freeze.
--
.~. Jean-David Beyer Registered Linux User 85642.
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