Wet Strength: The Use of Konnyaku in Hand Papermaking
by Catherine Nash
In 1995, I was fortunate to study with "National Living Treasure" Minoru Fujimori, at the Awagami Factory in Yamakawa, Tokushima, on the island of Shikoku in Japan. It is an area renowned for washi (paper) production since before the first written documentation of 807 A.D.. Established "to preserve and broaden the awareness for the beauty, strength and sensitivity of washi", today, Awagami Factory produces a variety of beautiful handmade papers and paper products and is especially known for indigo dyed washi. They offer workshops, conduct research and mount special exhibitions to further their goals. An amazing place!
It was at the Awagami Factory that I learned about konnyaku (pronounced kohneeyahkoo). Konnyakubiki is a paper treatment that I now use quite often and really appreciate the strength that it gives the dry sheet of paper, whether I am using it with dyeing (or other wet techniques), decorative surface techniques or leaving it unaltered. In Washi, The World of Japanese Paper from 1978, Sukey Hughes writes,
“Konnyaku is a tuberous root of the devil’s tongue plant of the Arum genus, the starch of which is used as a mucilage....The application of konnyaku makes paper strong and flexible enough to withstand the rubbing and wrinkling process; both treatments, in turn, render momigami [wrinkled, kneaded paper] much stronger, softer, and more flexible than untreated paper. Because the mucilage coats the paper’s pores, the sheet becomes not only wind and water-resistant, but the paper’s natural heat-retention qualities are enhanced; and yet the paper still breathes.”
A treatment of konnyaku imparts strength, in particular, wet strength, so that when paper is immersed in a dye bath for instance, the sheet stays strong and completely intact.
There are other Japanese treatments for strengthening paper such as shibubiki (using prepared kakishibu [persimmon juice] which yields a dark brown tannic acid originally used for flat paper fans), aburabiki (using kiri, an oil from the paulownia seeds that dry without being sticky, originally used to waterproof umbrellas and rain capes), and dosabiki (a 50/50 mixture of alum and nikawa [animal hide] glue, which imparts sizing and strength. But only konnyakubiki offers wet strength, without affecting the absorbancy of the sheet, so it will still absorb dye. Sponged onto a dry sheet of paper, the konnyaku strengthens the fiber to fiber bond of a dry sheet, so that when wet, it will not tear. It also protects the fibers from the alkalinity of the indigo dye bath.
Konnyaku root is sliced, dried and ground into a powder. My workshop notes indicate that the konnyaku is prepared by boiling the vegetable or its concentrate in water which solidifies in an alkali solution such as lime or soda ash to obtain a gelatin-like mucilage. Without the lime, konnyaku can be used as a vegetable gelatin sizing or glue.
The konnyaku solution is sponged over one side of a sheet of paper from the center out, let dry and repeated on the other side of the sheet. (A simple penciled x in the corner of the first side clarifies which side has been treated as there is no visual change.) The dry, treated sheet is ready for the dye bath or whatever other decorative, wet techniques are desired. It is also used to make momigami.
Momigami paper has a leather like surface that is very durable and creates a uniquely pliable sheet. It has been used historically for making paper clothing and is also used for book covers, etc..
The method for making momigami is this: Folding the four corners into the center, one crumples the treated dry sheets gently into a loose ball...one by one, they are taken up, and each packed into a tighter ball, turned round and round, squeezing and wrinkling them carefully but firmly. The sheet is unfolded, rewrapped, and the wrinkling and crumpling repeated. After three to four minutes of this, the sheet is then opened up, grasped at the near corner and rubbed together between the palms of the hand, paper rubbing against paper. The entire sheet is rubbed down, laid on a flat surface and stretched slightly by applying pressure with the hands in an outward direction toward the sides and corners. All the crumpling, rubbing and stretching may then again be repeated.
I buy a powdered version of konnyaku from Magnolia Paper that works wonderfully. You can call Magnolia Paper directly for information about konnyaku powder at (510) 839-5268 (address: 2527 Magnolia St., Oakland, CA 94607 USA).
Awagami Factory, Yamakwa, Tokushima, Japan.
Hughes, Sukey, Washi: The World of Japanese Paper. NYC: Kodansha International, 1978