Re: preserver for gum

Juan,
     You will know right away if your gum goes sour; it'll smell like a
combination of throw up and egg farts. It still works just fine, although
the increased acidity will make it thinner and increase insolubility without
exposure. I used my sour gums until I couldn't stand the smell any
longer; then I dumped them and used preservatives from then on. Rule of
thumb: if you're gagging, they gotta go.
      Preservative choices and amounts:
Several drops of formaldehyde per oz. gum

Several drops of 2% solution of methylparaben (2g in 100ml water)

0.25% solution of sodium benzoate (1g in 400ml water)

Thymol in isopropyl alcohol (100% alcohol, 1g thymol to 1 cc of alcohol)

Carbolic acid 1 drop per oz. gum

etc. etc.

I personally use sodium benzoate; I use 2 g for every 100g powdered gum I
mix up. That is stronger than the proportion above. I mix my gums 1+2 or
1+3. Works great.

Chris

----- Original Message -----
From: "JUAN MIGUEL JUSDADO" <jusdado@teleline.es>
To: "FOTOALTERNATIVA LISTA CORREO" <alt-photo-process-l@usask.ca>
Sent: Thursday, February 26, 2004 3:36 PM
Subject: preserver for gum

> hello to all.
> I am preparing an arabic gum solution for my impressions, 200 ml. of water
> and 70 gr. gum powdered.
> Can I use as preservative "FENOL" or "CARBOLIC ACID?"
> if it is this way, in what proportion?.
>
> thank you.
>
> Pardon for my English, text translated by computer.
>
>
Received on Thu Feb 26 19:09:33 2004