Sizing

There are a lot of variables in gum printing, a lot of ways to manipulate your final image. Some serve to benefit the finished print and some do not. Controlling those variables is one of the keys to good printing. The one that starts the ball rolling one way or the other is sizing.

Sadly, frustratingly, it’s also been the most confounding over the years. How well I’ve done these past couple of weeks will have everything to do with the quality of my prints in the coming year.

Sizing doesn’t mean measuring the paper. It means preparing the surface of the paper before printing on it. Most gum prints, including all of mine, are made on paper designed for print makers and watercolorists. Using those papers un-sized, the image will sink into the fibers of the paper. Staining becomes a real issue as well.

A properly sized paper keeps the image and all its detail on the surface of the paper and prevents staining as well. Even factory-made, store-bought paper is sized. Starch, egg whites, and gelatin are the most common materials used. But for the gum process, which tends to be pretty rough on paper, only gelatin is hard enough to withstand the abuse.

Sizing isn’t that great a job. More like a necessary evil.

With print side up, the paper is drawn carefully over the top edge of the vat.

Once a year, in the summer, I mix up 2 pounds of gelatin powder in 8 gallons of distilled water and heat to 125 degrees. Then 48 sheets of 22” x 30” paper are inserted into the bath and then removed from the bath and hung to dry. (The screen porch allows 6 rows by eight sheets, 48 in all.)

That process is repeated two more times on subsequent days depending on the weather and other circumstances. On the last day, 37% formaldehyde is added to a more diluted gelatin bath to harden the surface of the paper further and protect it from growing tiny life forms.

A gas mask is used on formaldehyde day.

All of that usually takes three or four days but I’m sizing a little more than twice as much as usual this year and that has really stretched the time uncomfortably close to Autumn. I had hoped it would all be done by now but the weather turned on me a couple of days ago. It has been a little too breezy and cool but tomorrow is supposed to be a little warmer.

Gelatin left in the vat overnight and scooped into the cooking pot.

See my website:  woodsedge.net