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

[phritz phantom <phritz-phantom@web.de>]

loris,
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.

regards
phritz


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,
> Loris.
>
>
> 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?
> >     
>