U of S | Mailing List Archive | alt-photo-process-l | Re: gum preservatves

Re: gum preservatves

I make my gum from powder using about 300 gm to make a liter. I preserve
this by adding 3 ml of a 1% solution of sodium benzoate per liter of gum
solution. I've been doing it this way for the last 7 or 8 years and it
works well for me. It lasts a long time and no souring or barfy smells.


Original Message:
From: Loris Medici mail@loris.medici.name
Date: Thu, 04 Sep 2008 15:34:32 +0300 (EEST)
To: alt-photo-process-l@usask.ca
Subject: Re: gum preservatves

FDA allows E211 in food unless concentration doesn't get over 0.1%. That's
why I'm thinking of reducing the amnt. in my next batch.

I first mix sodium benzoate then add gum, therefore it's also preserved
during time taking (at least 12 hours) dissolution process too.

Speculation alert: I'm not sure but I remember reading something like
"acidic gum is faster" (please correct me if I'm wrong), so maybe waiting
a little and adding preservative just before gum starts to rot could be
better. (Again, if I'm not mistaking gum gets more and more acidic as it
goes bad.)

What do you think?


4 Eylül 2008, Perşembe, 11:29 am tarihinde, Guido Ceuppens yazmış:
> The importer of the powdered gum I use once sugested "one teaspoon sod
> benzoate" per 100 grs of powder as a preservative. I have, since then,
> used
> 2,5 grs sodium benzoate per 100 grs dry powder and the gum, once
> dissolved,
> indeed lasts certainly at least for 2 years. Sodium benzoate is a food
> preservative (E211) and might (?) be less toxic than alternatives.
> Greetings,
> Guido
> 2008/9/4 Loris Medici <mail@loris.medici.name>
>> I guess most people use thymol nowadays.
>> Just for the record: I opted for sodium benzoate - because it was
>> cheaper
>> / easier to obtain than thymol. I use it generously; about 1g per 100g
>> of
>> gum (Probably overkill. But it's easier to weight 1g in place of dealing
>> with fractions...) and it preserves the gum pretty nicely with no
>> adverse
>> effect to my printing. (No problems even after 2 years.) Will reduce the
>> amnt. (tenfolds!) to 1g per 1000g of gum in the next batch (soon).

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