Loris,
I do not print extra large prints, 13x17 is the largest. But as far as registration is concened I would consider my papers to be dimensionally stable after the initial soak. Registration on a light table also helps to register what is impoortant in the print.
What I know for a fact and others have noted as well is that humidity at the time of printing makes a big difference. I have leaned never, ever to print my initial cyano layer on a rainy and cold day. I could never register these properly. Actually after I figured humidity is so imposrtant I could turn the heat up in the house and then some air contiioning to reduce humidity, or just wait for the sun to come out.
I have not used a hair dryer in years. Always just hang them to dry. I work in batches of several prints and by the time I an done coating my first print is ready for exposure.
The order of soak and size makes a difference IMO. My reasoning for sizing first and soaking later is as follows: gelatin shrinks more then paper when it dries, hence heavily coated papers will curl (like old B&W papers).
If one coats the paper first and then soaks it to shrink later, the gelatin will shrink when drying and paper will shrink in soak, so they will both shrink "in synch". No specific measurements here, but I feel it reduces the curl.
Marek
> Date: Wed, 29 Apr 2009 11:33:09 +0300
> From: mail@loris.medici.name
> Subject: RE: Gum over Cyanotypes
> To: alt-photo-process-l@usask.ca
>
> Thanks Marek will try this.
>
> It's amazing that you can print 10 layers w/o registration problems using
> the same negative. In my practice gum further shrinks paper when drying,
> moreso where it's thicker than average (= dark shades of the print). I can
> see the relief on the back of the paper starting with the 3rd layer... And
> it's pretty stiff to the point of being able to curl 300gsm paper in case
> of low key images. Now I'm confused. Will try thoroughly shrink the paper
> as you/Don and others describe and see what happens...
>
> Regards,
> Loris.
>
>
> 28 Nisan 2009, Salı, 9:41 pm tarihinde, Marek Matusz yazmış:
> >
> > Loris,
> >
> > I soak my papers (FA
traditional or extra white) in warm water for about
> > an hour. Move the papers around during the soak. My definition of warm is
> > to stick my hand and feel the temperature. If it feels cold it is too
> > cold. If it feels like taking the bath it is warm. Never had any issues
> > with multiple gum registration from layer 1 to 10.
> >
> > In the begining I tried a very hot water soak following the adivice from
> > the list, but found it unnecessary.
> >
> > Marek
> >
> >> Date: Tue, 28 Apr 2009 20:05:49 +0300
> >> From: mail@loris.medici.name
> >> Subject: Re: Gum over Cyanotypes
> >> To: alt-photo-process-l@usask.ca
> >>
> >> OK, thanks much, will keep that in mind for the next batch. What is the
> >> recommended max. temperature and nominal time for doing it right?
> >>
> >> R
egards,
> >> Loris.
> >>
> >>
> >> 28 Nisan 2009, Salı, 7:33 pm tarihinde, davidhatton@totalise.co.uk
> >> yazmış:
> >> >
> >> > Hi Loris,
> >> > PS.
> >> > The paper should be soaked in fairly hot paper to allow the fibres to
> >> > move one against the other and shrink fully. OR you could soak in room
> >> > temp water for 12 hours or so
> >> > David
>
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