RE: PVA for gum printing (Re: Artistico Unsized?)
Hi Katherine, I knew about that too. I have remained in the list all these years and followed closely most of the discussions especially when they are related to gum printing. Dave > -----Original Message----- > From: Katharine Thayer [mailto:kthayer@pacifier.com] > Sent: Saturday, August 25, 2007 11:06 PM > To: alt-photo-process-l@usask.ca > Subject: Re: PVA for gum printing (Re: Artistico Unsized?) > > Just to clarify: in my remarks I was referring solely to the > use of PVA as a substitute for gum in "gum printing," not > in some industrial application. Terry King has used it > extensively, in the form of "gloy," for his gum printing. > And Mike Ware's and his students' research had only to do > with this photographic use. And my own experience that I > described it was purely about printmaking, as > should have been clear. If you're interested, you'll find a ton of > information about PVA as a substitute for gum, in the archives. > kt > > > > On Aug 25, 2007, at 7:41 PM, Dave Soemarko wrote: > > > 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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