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

Re: gum preservatves

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.

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).