Japan’s Washi Paper Used to Mend Historical Documents at U.S. National Archives, Overseas Museums

By Takanori Yamamoto / Yomiuri Shimbun Correspondent

20:00 JST, May 8, 2025

WASHINGTON — The U.S. National Archives in Washington is making good use of traditional Japanese washi paper to repair historical documents.

Washi is light, strong, water-resistant and endowed with a beautiful texture. Since washi can last more than 1,000 years if kept correctly, it is highly appreciated among those in charge of preserving international documents.

The National Archives, which was established in 1934, houses as many as 13.5 billion pages of documents, including the Declaration of Independence and the original document of the Constitution of the United States. There are records that Japanese paper has been used to protect documents since the early 20th century. In the 1980s, washi was already an indispensable material in the field of preserving and mending documents.

The craft of washi is inscribed on UNESCO’s Intangible Cultural Heritage list and utilized to repair cultural properties at institutions throughout the world, such as the Louvre Museum and the British Museum. Washi is used to repair ancient documents at the Central State Historical Archives of Ukraine as well.

The value of washi is also attracting attention from the viewpoint of art.

“Washi excels in durability, which is proven by history on a timescale in millenniums,” said New York-based artist Hiroshi Senju. “[Washi] is more than just a culture. It is also recognized for its value as a civilization.”

Increased value of paper originals

The U.S. National Archives in Washington is proceeding with a large-scale project to digitize about 500 million pages of documents and make them public online by 2026. Yet the institution also regards the preservation of the originals as important as well. Japanese washi is highly valued for this purpose.

According to the National Archives, documents were not scanned in color in the early days of the digitization project. Therefore, the documents were digitized in black and white, without color information even if some text or seals were in color. There are concerns about the risk of blackouts and damage to digital files as well, so washi seems to give conservators peace of mind because it makes them feel assured that they can go back to paper anytime.

Yoonjoo Strumfels, a conservator at the National Archives, said that washi is essential to their preservation work because properly made washi can be used for a long time. Washi is characteristically less prone to degradation than other paper and also relatively resistant to environmental changes. Such traits make washi highly trusted for the conservation of documents.

Strumfels repaired a document that George Washington, the first U.S. president, wrote to the Congress by removing a silk cloth adhered for reinforcement and attaching a very thin piece of washi on the damaged area. The washi that was attached did not do any damage to the letters on the document and looked naturally blended to the point it was almost invisible, she said.

Of the different types of washi the National Archives utilizes for conservation, washi made from the kozo paper mulberry is the most commonly used because it has long fibers and excels in flexibility and strength. Washi made from the mitsumata shrub in the daphne family is suited to repair delicate items, such as photos, and washi made from the ganpi shrub of the daphne family has a pearly sheen that makes the paper preferred for occasions when the appearance of materials on display takes on importance. Apparently, the glue used at the National Archives to apply washi is made inside the facility using starch powder imported from Japan.

“While digitization is proceeding further, the degradation of data storage media and the demise of reproduction equipment are creating the problem that people cannot extract the contents from them,” Senju said. “When that happens, people go back to paper because they can read it without any equipment.”

Senju then stressed the significance of washi as a material that brings human memories to the future.

“Since this is the digital age, the multifaceted charm of washi is being rediscovered,” he said.