U of S | Mailing List Archive | alt-photo-process-l | Re: My own PVA glue sizing experience (attn: marek + the gum woesagain

Re: My own PVA glue sizing experience (attn: marek + the gum woesagain)

thanks for the outline on your coating process.
this is getting more complicated by the minute....i will try and read through the archive on the topic over the weekend.


Loris Medici schrieb:
My understanding is the "absolute humidity" is very important in gum
printing (and many other alternative processes).

Relative humidity (RH) percentage - as measured by ordinary
hygrometers - is not much useful alone to judge the water content of
air; you must also take temperature into account.

See this: http://www.tis-gdv.de/tis_e/misc/klima.htm

My workflow is to coat the paper, wait 5 minutes (to the point where
the emulsion becomes pretty tacky / almost dry, meanwhile I clean the
mixing vessel and brushes), then dry further with a hair dryer at low
setting (until it's dry to the touch), and finally humidify the paper
using an ultrasonic humidifier. The only part I have to be consistent
is the humidifying *ritual*. (Note the emphasis!) With this workflow,
my exposure times are constant and/or comparable all year round in
almost every possible indoor environment condition I may encounter
(given I'm using the same paper; different papers may hold different
amnt. of water - also, the emulsion formulations should be similar),
since there is always the same amnt. of moisture in the paper. I also
keep the paper isolated during exposure by placing an impermeable
plastic sheet under it; the felt in the contact printing frame's back
may draw or introduce moisture during exposure. (Something I learned
printing pop palladium.)

Hope this helps,

2009/10/23 phritz phantom <phritz-phantom@web.de>:

regarding humidity,
since you know a lot more about the subject than me,
do you think a change in weather (from a normal, sunny autumn day, to a
rainy day) could change the humidity within my apartment in a way that it
affects the drying of the gum emulsion?
iirc, you humidify your paper before coating and/ or printing?