Mulberry Bark

This bundle of fibrous, flattened twigs comes from the white inner bark or ‘bast’ of the paper mulberry tree (Broussonetia papyrifera), and is used for making Japanese handmade washi paper. The fibres extracted from this bark are extremely long, strong and silky, and can be used to produce extraordinarily strong paper that can be made ethereally thin and translucent as a result. This paper has been used to make everything from umbrellas, kites and window screens to calligraphy paper, books, and even paper balloon bombs that were deployed during the second world war. 

In order to make paper from the mulberry tree, its branches are steamed so that the outer bark shrinks back, making it easier to strip off the white bark on the inner stem. These strips of bark, also known as kozo, are then soaked in water for at least a day, and cooked for hours with the addition of an alkali, like soda ash, to remove any impurities. The fibres are then thoroughly washed many times, whilst inspecting for and removing any specks or impurities. Water is squeezed out of the cooked fibres, and they are then beaten with a rock, the bottom of a glass jar, or a similar heavy object. This pulp is now ready to be made into paper.

In order to make this kozo pulp into thin and evenly distributed sheets of paper, it is dispersed in a vat of water, and then scooped out with one flat screen (the Japanese method) or a mould and deckle (the Western method). Another essential ingredient in the making of washi paper is neri, a snotty, mucilaginous liquid derived from the root of the tororo-aoi plant. Long paper-making fibres like kozo and gampi tend clump together and get easily tangled, so it can be difficult to agitate them and ensure they are evenly distributed. Adding neri to the pulp and water mix changes the viscosity of the water so that the fibres float in the water, and it also covers each fibre with a slimy, negatively-charged coating that repels all the other fibres, ensuring they don’t get tangled. The neri also slows the drainage of water through the screen so that the papermaker has more time to rock the screen back and forth to evenly distribute the kozo fibres across its surface. 

This bundle of fibres was collected during a paper-making masterclass with book artist and expert paper maker Mandy Brannan. In her workshops, Mandy combines Japanese and Western papermaking techniques and uses a variety of materials including traditional bast fibres like kozo and gampi, leaf fibres like abaca and sisal, and more unusual materials like recycled silk ties, daffodil fibres and iridescent pigments. Mandy loves ‘the endless possibilities of using natural fibers that can be hand beaten, chopped, pigmented, manipulated and pushed 95% of the time – 5% of the time they do their own thing – that’s the nature of natural fibres!’ 

The earliest known paper fragments were discovered in north-west China, dating back to the Western Han Dynasty (206 BC– 8 AD). These fragments were made of coarsely pounded and unmacerated fibres of hemp and ramie. This papermaking technique using hemp and ramie was transmitted to Japan via Korea, and they began to use locally available kozo and gampi fibres. Imports of bast fibres from other countries began in 1950 and they have since become an important source of paper making supplies. Nowadays, kozo is exported from Thailand, China and Paraguay, mitsumata from China, and gampi from the Philippines, in addition to those grown domestically in Japan. These samples of kozo are from Thailand.