"Sized" watercolor paper

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"Sized" watercolor paper

Postby mjs » Tue Nov 18, 2014 8:37 pm

One of the things I do in my photography hobby is salt printing. Salt printing is an old process and like many "alternative processes" such as platinum printing, cyanotypes, etc. pre-coated paper for printing onto hasn't been made for many years so we prepare our own photographic printing paper, often from watercolor paper as a basis. I have a stock of such downstairs in my darkroom, including Rives BFK, so after my daughter loaned me her college watercolors and a brush I decided to test the printmaking paper to see whether the sizing applied to one side made a difference.

Yes, it does. Sizing is intended to slow the absorption of expensive photographic light sensitive silver nitrate solution into the fibers of the paper while the coating dries. Sizing is a coating of colorless gelatin, usually, and photographic suppliers such as Bostick & Sullivan can provide pre-sized paper or you can just buy paper and size it yourself with gelatin from the grocery store. It works to slow absorption of watercolors, as well as photographic emulsion, as one would probably expect. The paint just lies on the paper's surface in a little puddle, gradually seeping in over time. The other side of the paper, the unsized part, seems to work normally as you would expect watercolor paper to work.

So if you come across "sized" watercolor paper, or watercolor paper prepared for alternative photographic printing processes, be wary of it. Sadly, you can't really tell by just looking at it whether the paper has been sized or not, although you can probably tell by applying a drop of water and seeing whether it soaks in quickly or seems to take a while.

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