RE: Gum Preservatives
I wouldn't too. I used thyme water (which contains considerable amnt. of thymol) in my first batch (3ml into 300ml) and the gum solution went bad in just 2 weeks (serious mold growth). I used food grade Sodium Benzoate in the second batch (according to the following recipe: http://www.usask.ca/lists/alt-photo-process/2005/apr05/0247.htm. Please note that I mean 5g Sodium Benzoate per 200g Gum Arabic powder. My gum:water weight ratio is 1:2 - 100g gum powder into 200g/200ml water - that's quite different from Guido's recipe!), and it's fine after 2 weeks - it looks, smells and works (and it works well!) just as it was 2 weeks ago... (I'm currently printing on aluminum) Hope this helps, Loris. -----Original Message----- From: Katharine Thayer [mailto:kthayer@pacifier.com] Sent: 06 Aralık 2006 Çarşamba 05:19 To: alt-photo-process-l@usask.ca Subject: Re: Gum Preservatives You could, but I wouldn't. What you need is a biocide, while glyoxal functions as a crosslinking agent. If you used enough glyoxal to crosslink the gum enough to discourage mold growth, I suspect it would also render the gum insoluble (thus unusable). In my experiments hardening gum for painting, I found that a drop of glyoxal hardened 5 ml of gum to a crystalline state. In general, I'd say you want the crosslinking of gum to occur in the exposure phase, not before. Katharine On Dec 5, 2006, at 6:31 PM, Michael Koch-Schulte wrote: > Can I use a few drops of Glyoxal in gum arabic as a preservative? > I'm mixing > the gum from powder. > ~m
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