As archive conservation techniques developed throughout the late 20th century, conservators experimented with various materials used to line fragile items and enable delicate repairs. In our archives, we can still see some attempts using nylon gauze or netting alongside linen backings and traditional Western handmade papers.
Japanese papers had been used in fine art conservation for some time. As they became more readily available and affordable, archive conservators began to utilise these beautiful and versatile papers.
Japan has a long history of papermaking techniques that have survived over the centuries. Japanese papers are highly valued for their quality, strength, and purity, making them ideal for preservation purposes. These unique qualities stem from traditional production methods. Common types used in conservation include the very thin Tengujo and the robust Sekishu-shi papers.
Japanese paper fibres
The numerous Japanese papers used in conservation are made from three main fibre sources: Kozo (mulberry), Mitsumata and Gampi. Each has its own unique characteristics.
- Kozo: Papers made with Kozo are the most common in conservation. Kozo has the longest fibres and makes the strongest paper, even when thin. It is often used to line fragile paper items. It is grown as a farm crop, and the branches are cut annually. The plants will regenerate continually for about 40 years.
- Mitsumata: Mitsumata has shorter, weaker fibres compared to Kozo. The papers it produces are slightly weaker, softer and more opaque than Kozo papers, and they are more commonly used for infilling missing areas when repairing archival material. While it is also grown as a crop, Mitsumata takes 3 to 5 years to regenerate, so it is a more expensive paper.
- Gampi: This is the oldest of all the papermaking plants in Japan. Gampi has the shortest and weakest fibres and is the most absorbent, with a warm colour and a high, smooth lustre, it exhibits a significant degree of translucency at lighter weights. Superior quality Gampi fibres are rare, so this type of paper is extremely expensive.
Japanese papermaking
Though some of the Japanese papers used in conservation are machine-made (for example, large rolls for lining maps), the majority are still handmade in Japan using ancient methods to increase longevity, neutralize acidity, and purify or lighten the paper. A wide variety of fibres, sizes, textures, strengths, thickness, transparency, and hues are available, allowing Conservators to source the perfect paper for specific tasks.
Production begins by removing the outer layers of stems until only the white middle part remains. The stems are then soaked in water to soften. In ancient times, branches were steeped in the river for 2 to 3 days. After soaking, the fibres are removed by boiling them in large vats filled with baking soda. Any dark particles are taken out by hand while immersed in cold water.
The fibres are then pounded thoroughly with a wooden mallet placed on a stone slab.
The pulp is then blended, mixed and scooped up using a frame with a screen called a ‘suketa.’ The paper produced in the frame is then stacked and pressed to remove any excess moisture. After the sheets are pressed, they are placed on a large board and dried in the sun. The sheets are then checked for thickness, tears, or impurities and chosen sheets are cut into the preferred size using a special knife.
Conservation methods using Japanese papers
Japanese papers provide conservators with a strong and durable material for sympathetic repairs that blend well with original materials. The long fibres, particularly in Kozo papers, provide exceptional strength, even in very thin sheets. The traditional paper making methods used result in paper with few impurities, making it less likely to degrade over time. These papers are naturally acid-free, which is crucial for long-term preservation.
The flexible nature of Japanese papers means they are easy to work with, even when wet, making them suitable for highly intricate repairs. Conservators need to consider reversibility to ensure material can be returned to its original material composition. When using starch paste, Japanese paper repairs can be removed by adding moisture, allowing for future adjustments if needed.
Some Japanese papers are naturally translucent, which means they make excellent lining materials as they do not obscure information and easily blend in to strengthen weak paper. Thin Kozo papers can be used to reinforce tears and stabilize fragile areas on paper without obscuring text or watermarks.
Conservators also use Japanese papers to interleave documents and protect them without adding bulk. They can also be used to make flexible hinges to attach delicate documents to archival board for display.
To summarise, the unique, high quality materials and traditional production techniques used in the manufacture of Japanese papers provide conservators with a wide range of beautiful, strong paper of varying thickness, tones, and textures to enable highly compatible repair techniques on a range of archival materials.
Images
Select image to view a larger version.
- Ancient Japanese Paper Making (Photo Credit: Waseda University Library)
- Thin Kozo paper example
- Japanese paper making (Photo Credit: Tenjin Sanshi Japanese Paper Factory)
- Japanese papers used to line a map
- Fine Kozo paper used to repair a fragile paper document