U of S | Mailing List Archive | alt-photo-process-l | Re: gum question

Re: gum question



Preshrinking works for some paper and destroys the sizing in others.

It appears that the length of time may be more important than temperature: less than 1/2 hour may not be long enough for the paper fibers to get thoroughly wet. I try to use hot water for at least one hour.

Some papers can' be presoaked at all, hot or cold. An earlier run of the Cranes Parchment that worked with platinum perfectly with no pre- treatment would become unusable after a soak in 1% oxalic acid. I found that out the hard way. It soaked up the emulsion like toilet paper!

Another variable to contend with.

Sam

On Jun 9, 2008, at 5:04 PM, henk thijs wrote:

Hi Judy,
Preshrinking in 'not-hot-water' reminds of the discussion some time ago about the large gumprints made by Jean Janssis, belgian gum printer ( he can be found in musea all over the world); when i asked him about preshrink , he said he did not sized after two times of preshrinking in -cold- water , and he did not have any registering problems he said.
Any luck on the list with this method?; it did not work for me.
Henk




On 9 jun 2008, at 4:24, Judy Seigel wrote:

On Sun, 8 Jun 2008, Diana Bloomfield wrote:

... though I did shrink and size the paper for that particular zone plate, I had done some others where I hadn't done any pre- shrinking, and I didn't seem to have trouble re-registering the negative. I guess that's only because the images were so blurry and indistinct, anyway, that the edges weren't clearly defined from the get-go.

It occurs to me to wonder if .... since you're dancing around minimum pre-shrink, minimum pre-stress, or "virginity," so to speak, it might make a difference if the pre-shrink wasn't HOT. A while back I tested a looong preshrink in room temp water vs. the HOT short preshrink that's the norm.

I found that the long room-temp soak gave the same amount of shrink that the short hot soak did... I don't remember the times, tho I could probably find them in Post-Factory, but it occurs to me to wonder if the room temp soak might "raise the nap" or rough up the paper less than the hot.

Of course you seem to be doing OK the way you're doing it, & no need to fix it, if it ain't broke, but I mention the thought, should a snag arise.

J.