About sizing gum: Hey -- READ THE LIST !!!
Don't people on this list read the list? I've been using glyoxal to harden gelatin size for gum printing for -- probably 15 years. Maybe more. I put it on the list (not to mention Post-Factory) in the days of Mike Ware, who was the first AFAIK to mention it, practically in the 18th century... And as far as I knew til now (from what I've read & printers I've spoken with) it had become general.. I think gluteraldehyde (the hardener in some other potions) has also been used, but the exact strength that worked was a matter of trial and error -- as Christina Anderson described on list. The glyoxal seems to work with everything, it has a faint odor, but was perfectly usable indoors in winter with all windows closed, and no "outgassing," either drying indoors or when brought in dry (as formaldehyde does). There's also the fact that in the US, at least, it had become awfully difficult to get formaldehyde, the reason being (allegedly, tho who knows?) that it's used to make ... what? crack cocaine? Something like that. The only drawback with glyoxal, in my experience, is that the mixed solution doesn't keep well. (IME it keeps reasonably well kept full strength, tho not long-term once opened.)... So don't mix more than you want for a day or two.. It's used in the same proportion to water as the formaldehyde... (I assume that what's giving the odor problem which -- Jeremy doesn't mention -- is formaldehyde ... Not only painful, but not good (I'd assume) for pets and children. I've never heard of a problem in what paper it's used on -- I've used it on every paper I own, which feels like every paper ever used for gum and then some. The only drawback is that it doesn't keep well in solution -- certainly not as long as formaldehyde (which probably keeps until the end of time -- morticians will embalm yr corpse in it). As for chrome alum & company, it's my understanding that they are quite poisonous, and remain so, and not what you want to drop into the water table (along with all those hormones and pthylates). Whether glyoxal is poisonous or not, it does break down (as I understand these matters, but admit that I am not a chemist), and certainly by the time I dispose of it seems entirely attenuated. I don't understand the space problem in any event -- I size in the studio which is also where I sleep. I put the sized paper on screens which can be stacked up to the roof.... with a little electric fan in front. What's the problem? (Admittedly I size in the AM. But I've also hung sized papers in the hall downstairs. Not a problem.) PS. As for the "slick hard surface" Katharine mentions, I've never found that, but figure it could be from too thick gum or too strong hardener, or both? PPS: I haven't bought glyoxal lately, having had an excess of sized paper, which, contrary (like so much else) to what I'd read in books, seemed to keep almost indefinitely. But last I heard, Photographers' Formulary had it. J.
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