Pre-shrinking paper
You may have heard people in the alt photo community talking about pre-shrinking their paper and wondered why. Essentially, it’s because we use high-quality watercolor paper in a way that it’s not really made to be used, and are forcing it to absorb more water than it was made to absorb while still retaining its shape.
During the development and rinsing process, I routinely soak paper an hour, and sometimes more than an hour. This leads to the paper shrinking to a slightly different size than it was before. This isn’t a big deal if you’re only making a 1- or 2-layer print, but most gum printers do 3-8 layers, and the paper can shrink quite a bit over that time. By shrinking the paper before your first negative, the hope is that, like your favorite t-shirt, it shrinks once and then stays that size so you can maintain registration.
About Watercolor Paper
Watercolor paper is made of cotton rag, but the amount of cotton within the paper can vary. A cheaper watercolor paper could be made with up to 55% filler, such as wood pulp. They will absorb water (and emulsion) differently than the more expensive, 100% cotton papers.
As part of the paper-making process, paper is soaked or coated in sizing. Sizing is usually a combination of gelatin or glue and other proprietary things. It allows the paper to absorb a certain amount of water while leaving the brilliant pigments of applied watercolor paint on the surface, but that’s not always what you want with printing. For instance, sizing is extremely important for gum printing, because you do not want the gum mixture to soak into the paper. This will cause staining, which will shrink the tonal range of your print (i.e. muddy your highlights and lower contrast overall). Yet, not as important for cyanotypes.
Sometimes this sizing washes away in the pre-soaking process and needs to be replaced. Because paper manufacturers keep their sizing recipes a closely-guarded secret, you can’t be certain from paper to paper what will happen when you pre-shrink. When I do a tri-color print with cyanotype as the base, I apply my sizing after the cyanotype layer since it’s not that important with cyanotypes, but can make or break the print as I add yellow and magenta.
There are lots of papers to choose from, but since this post isn’t about watercolor paper specifically, I will just say that my two favorites are Fabriano Artistico, hot press, 300gsm (140lb) weight, and Hahnemühle platinum rag, which is a paper specifically designed for alternative photography printing. I’m currently trying to see how many layers I can do on Hahnemühle without needing to pre-shrink it. I have found that if I’m doing something smaller than 8x10 I can get away with it up to about five layers. I’ve noticed Fabriano Artistico shrinks more, so I have to pre-shrink this paper if I’m doing anything more than a single-layer print. A note: paper on watercolor pads will state it has been “pre-stretched.” This is not the same thing as pre-shrunk. This will not be sufficient for your uses, since you will have to remove it from the pad, so you will probably still want to pre-shrink this paper.
Temperature + Time
You should consider temperature carefully when you pre-shrink your paper. The sizing could be removed by warmer water, which means you will have to resize your paper before using it. I pre-shrink for an hour in 140ºF/60ºC, then hang the paper to dry. Obviously, the temperature of the water won’t remain that temperature the whole time, which is why some people find they have to pre-shrink twice.
How to pre-shrink paper
I use my largest trays so that the papers have room to move and get full coverage. If you used pad paper, remove all the gummy bits on the edges before you start. Once you start adding paper, move quickly.
Soaking
Add the first piece to your warm water bath and dunk to fully submerge it. Wiggle it around to remove air bubbles.
Once it’s wet on both sides, add the second piece. Dunk to fully-submerge and wiggle to release any air bubbles that may have collected under it. Then hold the two pieces of paper together like a sandwich and flip it over (so top paper is now on bottom).
As you add paper, continue wiggling paper around and flipping the paper “sandwich” over so one piece isn’t always on the bottom or top of the pile.
Once all paper is added, let soak for at least 15 minutes. I let mine soak for an hour.
Drying
Fabriano Artistico pad paper hanging to dry
When you hang to dry, either hang everything by the long end or hang everything by the short end. Whatever you choose, continue to hang that paper by that end all the way through your printing process.
Prepping paper for use
Once your paper is bone dry, you will find that it is mildly-to-horribly buckled. I literally iron it… it’s cotton after all! I iron my paper briefly on steam setting, checking carefully to make sure I’m not leaving marks on it. I typically decide at that point which side is the “better” side and I always put process notes on the backside of my paper. At this point I will note what kind of paper it is, and that I have pre-shrunk it.