Gum print registration

Darrin · Dec 3, 2019

Hey,

ive has an issue with registration. I’ve used pins and tape to align my prints and I’ve used registration marks as well but even though I wash and size my prints but it seems like the paper always shrinks. Does anyone know what I can do to try to get my layers registered?

kevs · Dec 4, 2019

Hi Darrin, you need to pre-shrink the paper before making your prints, see http://www.alternativephotography.com/gum-printing-basics-how-to-make-a-gum-print-troutner/ .

Como · Dec 4, 2019

Besides pre shrinking, the moisture of the print is of influence. When the print is too wet it will be larger then your negative. Drying with a hair dryer will help to shrink it a bit.
When the print is very dry it sometimes is smaller then your negative. Moisturing it a bit with a plant sprayer and wait a couple of minutes.

Most people have their registration marks in the corners. But when you place the marks in the middle of the sides the center of your print will always be registered. The corners can be out of register but that is of less importance.

Andrew O'Neill · Dec 4, 2019

I use HPR paper. I preshrink it twice in warm water. I use push pins to register... sometimes I don't even bother, especially when the cyan is laid down first. I just eyeball it. The key though is to preshrink your paper. make pencil marks on the backside of the paper. You can see how much it will shrink. Some papers that I have used need more than two shrinking baths.

Darrin · Dec 4, 2019

Oh ok. I was only doing one shrinking bath. I’ll try doing 2 or 3. I’m using arches cold press paper. Generally I do the yellow, magenta and cyan last. Should you put cyan down first?

Andrew O'Neill · Dec 4, 2019

Darrin said:
Oh ok. I was only doing one shrinking bath. I’ll try doing 2 or 3. I’m using arches cold press paper. Generally I do the yellow, magenta and cyan last. Should you put cyan down first?

When I use cyanotype for the blue layer, yes. I have also done the blue first with water colour, because sometimes the image looks better... If the blue goes down, pin registration is not necessary, in my experience.

Darrin · Dec 10, 2019

I'm going to try that out. Is it true that if you do a cyanotype layer that you don't have to size the paper?

Como · Dec 11, 2019

First you make the cyanotype on unsized paper. Thereafter you size the paper. After sizing you can apply the gum-bichromate layers.

Bob Carnie · Dec 11, 2019

Darrin said:
I'm going to try that out. Is it true that if you do a cyanotype layer that you don't have to size the paper?

Yes this is true you do not have to size multiple layer prints on cyanotype or palladium for that matter.
Pre shrinking the paper is a key and of course using premium papers.

Como · Dec 11, 2019

It also depends on the paper u use. I have used Montval Canson and Bergger COT 320 and both papers needed sizing after applying the cyanotype.
When you do not size, the gum emulsion will sink into the paper and never wash out any more.
I always size with PVA diluted with the amount of water, about 20 ml for a sheet of 25 x 35 cm

Bob Carnie · Dec 12, 2019

Como said:
It also depends on the paper u use. I have used Montval Canson and Bergger COT 320 and both papers needed sizing after applying the cyanotype.
When you do not size, the gum emulsion will sink into the paper and never wash out any more.
I always size with PVA diluted with the amount of water, about 20 ml for a sheet of 25 x 35 cm

that is odd I use Cot with no sizing and if the print is dry the coating of the gum layer sits nicely and after processing the gum remaining with pigment slowly seeps into the paper.

jim10219 · Dec 12, 2019

I just use registration marks at the corners of my sheet. I've tried pins, and don't like them.

I used to have problems with shrinking paper, but have since learned that you have to preshrink the paper really, really good first. With some papers, you have to preshrink more than others. Sometimes, I'll even preshrink them in hot water two or three times for about an hour each time before my first print.

The downside to preshrinking paper is it loses it's sizing. So I'll usually have to size the paper before my first printing. Then, I'll often have to resize the paper before each additional layer. I use diluted PVA for sizing, and I'll often have to increase the ratio of PVA to water as I progress along a print, as the paper seems to get easier to stain the more times you soak it.

It's taken me lots of trial and error to get my system down. And even then, I'm constantly having to tweak it.

Como · Dec 12, 2019

Bob Carnie said:
that is odd I use Cot with no sizing and if the print is dry the coating of the gum layer sits nicely and after processing the gum remaining with pigment slowly seeps into the paper.

To be honest, I did a lot of gum printing with Canson. Sizing was absolute neccesary with that paper.
Afterwards I have made prints with Bergger. I didn't change my workflow so I sized the paper (afer cyanotype). Wether it was neccesary or not I did not investigate.

Andrew O'Neill · Dec 12, 2019

Como said:
To be honest, I did a lot of gum printing with Canson. Sizing was absolute neccesary with that paper.
Afterwards I have made prints with Bergger. I didn't change my workflow so I sized the paper (afer cyanotype). Wether it was neccesary or not I did not investigate.

When I used cheap paper like Stonehenge, it absolutely needed to be sized for gum. For gum over cyanotype, I had to first give the paper an acid bath (10% sulfamic acid), otherwise the cyanotype looked anemic... then the cyanotype image was sized with a 6% gelatin solution (allowed to soak in and then squeegeed). I have never gone back to those cheap papers since started working with HPR.

jjames100 · Dec 31, 2019

Como said:
It also depends on the paper u use. I have used Montval Canson and Bergger COT 320 and both papers needed sizing after applying the cyanotype.
When you do not size, the gum emulsion will sink into the paper and never wash out any more.
I always size with PVA diluted with the amount of water, about 20 ml for a sheet of 25 x 35 cm

I haven't tried PVA yet so does it hold up under multiple washes? Do you have any trouble with flaking? Is it as good as hardened gelatin size? Thanks.

jim10219 · Dec 31, 2019

jjames100 said:
I haven't tried PVA yet so does it hold up under multiple washes? Do you have any trouble with flaking? Is it as good as hardened gelatin size? Thanks.

In my experience, PVA doesn't flake. It does, however, wash off with multiple washes. Sometimes, a single coat is all you need for four color gum over cyanotype. Sometimes you might have to reapply after every layer (especially with casein prints with strong pigments which soak deeper into the fibers and can require a sodium carbonate bath after development). It's fairly consistent from print to print, but varies significantly from paper to paper or pigment to pigment. So I recommend doing some experimenting first with your current setup and see what works best. The good thing about PVA is it's easy to mix and apply and dries quickly. So I can mix up and coat a few sheets in PVA and have then dry and ready for emulsion in under an hour.

Como · Jan 1, 2020

Jim10219 has given a complete answer. The only thing I can add is that PVA is somewhat glossy while gelatine is matt

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