[alt-photo] Re: Gum solution help needed

[Loris Medici]

  In my case, it was 2 litre jar with little (100-150ml) in bottom. 
Maybe the students in the photo centre didn't pay attention to seal the 
bottle carefully. Anyway, I think many will prefer something other than 
formalin for the job -> especially considering it's hard to purchase in 
some parts of the world.

Regards,
Loris.


08.08.2010 16:52, John Brewer yazmış:
> I mix up 1 litre at a time and that lasts about two years plus and I've never had any problems. Obviously it is kept in a sealed jar.
>
> J.
>
> -----Original Message-----
> From: alt-photo-process-list-bounces at lists.altphotolist.org [mailto:alt-photo-process-list-bounces at lists.altphotolist.org] On Behalf Of Loris Medici
> Sent: 08 August 2010 14:47
> To: The alternative photographic processes mailing list
> Subject: [alt-photo] Re: Gum solution help needed
>
>    FWIW, formalin indeed preserve the gum solution, BUT, you have to use
> it up relatively quickly: Formalin will evaporate slowly, to the point
> of not being able to protect your solution - especially true in case
> there's a little remainder solution in a large container. At least
> that's my experience...
>
> Therefore, my preference is towards dry / soluble preservators. I
> personally use sodium benzoate, but aspirin looks definitely very
> interesting - especially for people who don't want to purchase / stock
> an extra chemical (such as thymol + alcohol or sodium benzoate or the
> dangerous mercuric chloride) in order to preserve their gum solutions.
> (E.g. students, workshop participants et. al. ...)
>
> Thanks Philippe.
>
> Regards,
> Loris.