RE: PVA for gum printing (Re: Artistico Unsized?)
Yes, it has been used a lot especially in industry, so if I ever get to do testing/research, it won't be the technical in academic sense (like the study of how this particular polymer polymerize or the study of chemistry of it) but rather the application of it in printmaking. Dave > -----Original Message----- > From: Katharine Thayer [mailto:kthayer@pacifier.com] > Sent: Saturday, August 25, 2007 5:19 PM > To: alt-photo-process-l@usask.ca > Subject: PVA for gum printing (Re: Artistico Unsized?) > > For whatever it's worth, PVA (polyvinyl alcohol) has long > been used as a substitute for gum; since dichromated PVA > apparently behaves chemically like dichromated gum arabic > (the crosslinking mechanism is assumed to be the same) the > research on dichromated PVA is what we use to try to > understand the chemistry of dichromated gum, since there's > virtually no research on the mechanisms of dichromated gum per se. > > There are many variations of PVA and not a consensus on what PVA > works best as a substitute for gum in a dichromated colloid > process; > it comes in an endless variety of types depending on > molecular weight (length of chain) and degree of hydrolysis > among other characteristics. > > David Hatton, several years ago, provided us a wonderful link > to a site that explained how the different PVAs behave, > depending on their different characteristics. I went looking > in the archives for the link and actually found it (my > success at finding things in the > archives hasn't always been so good) but when I clicked on > the link, > it took me to a page that was all in perhaps Korean, so I > guess that link doesn't work any more. > > Mike Ware, several years ago, shared with me some research a > student of his did to determine what PVA works best for gum > printing; he gave > me permission to share that information, with proper citation. > Here's an excerpt of the post where I shared that with the > list, gleaned from the list archives: > > "He said that they settled on was a "polyvinyl alcohol-acetate; i.e. > only partially hydrolysed co-polymer, which is much more > easily dissolved in water than the pure alcohol. We found an > 88% hydrolysed PVA, with an RMM around 25 kD in 20% w/v > solution, to offer the best all-around results-- comparable > to a 14 Baume Gum." > > "If you make any public use of this information in the > future, please acknowledge the original experimenter, by citing: > > Stephen Beckett, M. Phil. Thesis, University of Derby (UK), > November 1993. (A private communication from Mike Ware)." > > ______________________________________________________________ > __________ > _ > > > Just out of curiosity I tried printing with PVA some time > ago, in the > form of "gloy." Keith Gerling was kind enough to share a thimbleful > of his supply of gloy with me, so I was only able to make a > couple of > small test prints, but in that limited experience, I couldn't tell > any great difference from gum. It looked like gum, felt like gum, > coated like gum, printed like gum (same exposure as my usual, same > number of steps (8) compared side by side with my gum of choice at > the time, using the same pigment mix, etc. > Katharine > > > On Aug 25, 2007, at 6:37 AM, Dave Soemarko wrote: > > > First time I heard of it. I just did some search, and it looks > > interesting. > > > > Thanks for the info! > > > > > > Dave > > > > > > > > From: henk thijs [mailto:henk.thijs@hetnet.nl] > > Sent: Saturday, August 25, 2007 9:10 AM > > To: alt-photo-process-l@usask.ca > > Subject: Re: Artistico Unsized? > > > > > > On 25 aug 2007, at 14:39, Dave Soemarko wrote: > > > >> << What is of no interest for the paper, but just for info: > >> he uses no gumarabic -he hates formaldehyde or similar- but uses > >> Mowiol 88 in stead .... >> > >> > >> > >> Henk, > >> > >> What is Mowiol 88? > > > > > > > > Hi Dave, > > On the box is written: > > > > Polyvinyl alcohol 8-88 ; small clear crystals , if you want to use > > it and needs some info about percentages etc. just ask. > > I ordered it from Kremer Pigmente (on the box the name FLUKA is > > obviously the manufacturer). > > Last time i contacted them, they told me that the 8-88 is not > > produced anymore, but the 4-44 would be the same , apart from the > > concentration (!) > > cheers, > > Henk > > > > > > ------------------------------------ > > www.thijs-foto.com > > ------------------------------------ > > > > >
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