The world’s thinnest paper

(written by lawrence krubner, however indented passages are often quotes). You can contact lawrence at:, or follow me on Twitter.


Inside the factory, the air is steamy from warm baths of alkaline water in which bushels of kozo — the stems of mulberry trees — are soaked. Workers remove dirt from the kozo and pound it into strands of pulpy fiber, which they lay in a tub containing water and neri, a thick viscous liquid that is derived from the tororo-aoi plant, also known as sunset hibiscus. Reacting with the neri, the kozo fibers gain a sticky, gummy quality, which allows them to be broken down even further and pulled apart into long white ropes, which are removed from the tub and spread out evenly over a screen. The ropes are massaged together and flattened to the width of a couple of spiderweb-like fibers. As the liquid dries away, these fibers are left woven together, clinging to each other in a delicate sheet of paper.

Tengujo can help reinforce and repair damages from many sources. Ms. Choi calls it “the bread and butter in paper conservation” and “probably the most gentle way of reinforcing anything.” Sometimes tengujo is used for spot-treatment, other times to completely line a manuscript. Its long fibers provide structure and support while remaining almost completely unnoticeable.

…About six years ago, Mr. Chinzei was asked by the National Archives of Japan to develop a tengujo that weighs 1.6 grams per square meter, thinner and lighter than any other paper in the world at the time. It took him two years of trial and error, minutely varying the pressure of the pounding machine, the speed of the mixing, the density of the fiber and neri in the water. “My workers and I were amazed we could make it,” Mr. Chinzei said.

The width of this thinnest tengujo is the same as the diameter of a single kozo fiber: 0.02 millimeters. Thinner than human skin. No other company has been able to replicate it.

It is now sold around the world for paper conservation. Chinzei has sent rolls to the Library of Congress, the Louvre, the British Museum and the Yale Center for British Art.