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)."
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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
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www.thijs-foto.com
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