Re: Hardening With Glyoxal: One Shot?
I was just thinking "whither Ryuji?"....So are you advocating using both a biocide and a hardener with gelatin? If the hardener's not a biocide are people fooling themselves? Should we separate biocides and hardeners into separate categories? My stock gum arabic I assume has a biocide already in it. I understand the purpose of the biocide but has the term "harden" been applied too loosely in the past? Hardening without a biocide presumably still leave the gelatin open to attack. For my own purposes I'd like a method of being able to size small amounts of paper. So ideally a stock solution of gelatin that can be rewarmed and then I'll add in drops of my hardener of choice, that sound about right? Thanks Ryuji! ~m ----- Original Message ----- From: "Ryuji Suzuki" <rs@silvergrain.org> To: <alt-photo-process-l@usask.ca> Sent: Monday, May 07, 2007 1:32 PM Subject: Re: Hardening With Glyoxal: One Shot? > Gelatin solution does not keep very well even if refrigerated, unless a > small amount of biocide is added. A couple of days may be ok but > bacteria grow very well on gelatin solution. They break down gelatin > molecules to smaller molecules and their gelling property is affected. > > http://silvergrain.org/wiki/index.php?title=Biocides > > Compounds that hardens gelatin molecules should not be counted on > because they bind with gelatin molecules and not available to kill > bacteria. Ones that are photographically inert and don't react with > gelatin should be added, if the sizing solution is to be kept for later > reusing. > > Hardener is best added immediately prior to coating, as already > discussed. >
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