This woodblock print Notes on Sericulture (silk-farming) was designed by the Japanese artist Yoshitora (active c 1840–80). He trained at the Utagawa school that specialized in the genre of ukiyo-e or ‘pictures of the floating world’ [1]. The three main themes for ukiyo-e paintings and woodblock prints were beautiful women, actors and landscapes. Printed on a sheet of paper measuring 37.15 × 25.4 cm the print is in the collection of the Los Angeles County Museum of Art. The text is written in old Kanji—Japanese script that includes symbolic Chinese characters—and refers to ‘things to remember about sericulture’ (F. Onodera, personal communication). The print is one-third of a triptych Sericulture Tips that was created in 1847–52 and published by Izumiya Ichibei [2]. Sericulture depends on moriculture (mulberry tree farming) because most commercially produced silk comes from the caterpillar of the Bombyx mori moth that feeds exclusively on mulberry leaves [3].
Utagawa Yoshitora, Notes on Sericulture, 19th century, colour woodblock print, image: 14 1/4 × 9 11/16 in. (36.2 × 24.61 cm) sheet: 14 5/8 × 10 in. (37.15 × 25.4 cm), Los Angeles County Museum of Art, anonymous gift, photo © Museum Associates/LACMA.
The print shows eight female workers engaged in different stages of sericulture. In the upper zone, two workers pull down and remove mulberry tree branches to harvest leaves for the caterpillars and to encourage new and dense leaf growth at manageable height. One holds a pruning hook as does the worker in front of her who is tying the branches into bundles. In front of her another worker removes leaves and drops them into a long basket. Just to the left of her a colleague loads a cocooning frame with circular trays that contain leaves and white caterpillars (silkworms). Across to the left and below, another worker stacks bundled branches. The lowermost worker may be sorting hatched moths to provide the next generation of eggs. The worker to the right delivers further cocoon trays. The other triptych panels show the cocoons being washed and hung to dry; and silk threads being reeled. Each caterpillar spins a silk thread about 1 km long and made of two proteins: a soluble sericin coat and a fibroin core. Most sericin is removed during boiling and reeling [4].
The woodcut indicates that workers are at risk of developing occupational illnesses and injuries related to hazards such as posture; the use of sharp tools; and any fertilizers, herbicides and pesticides used in moriculture. Airborne proteins from insects are recognized to cause respiratory allergies such as asthma, conjunctivitis and rhinitis. Insect-induced respiratory allergies occur among a variety of workers such as laboratory staff who work with locusts and grain handlers because of the wheat weevil. In sericulture, workers are exposed to pollen from the mulberry trees; and airborne protein particles from moulted caterpillar skin, cocoons, excreta and moth scales. Notably, aerosolization occurs when cocoons are boiled in water to dissolve sericin from the outer layer [5]. As with other causes of occupational asthma it is important to maintain good occupational hygiene to reduce exposures to dusts and aerosols, to identify work-related symptoms early and to remove workers from further exposure if they have developed occupational asthma.
Sericulture originated in China and was introduced to Japan between the 3rd and 2nd centuries BCE. Similarly, paper manufacture and woodblock printing originated in China. These crafts were introduced to Japan in the 8th century by Buddhist missionaries. Woodblocks were produced in the main publishing centres of Osaka, Kyoto and Edo (Tokyo) as illustrations for religious books [1]. During the 17th and especially the 18th centuries a shift from an agricultural to a mercantile economy generated a class of affluent and literate merchants [1]. Woodblock artists seized the opportunity to produce pictures for this new clientele. They also provided illustrations for secular books covering a range of subject matter and scenes of Japanese everyday life that appealed to the many who could not read [1]. The featured print would serve as an educational resource for those who could not read.
Black ink prints were coloured by hand until the early 18th century when a colour print method was developed using blocks with two colours. In about 1764, the full-colour print block was developed [6]. At that time, Japan was an isolationist state. There was little exchange of artistic techniques with other countries; so, woodblock art developed as a unique Japanese art form. From 1854, sea ports were re-opened for international trade and for travel [1]. Soon, Japan became the world’s largest silk producer and the foreign earnings helped to fund Japan’s modernization and industrialization [7]. However, exposure to Western culture had other consequences and Western art forms began to outcompete woodblock prints. Woodblock artists replaced traditional vegetable and mineral dyes with vivid aniline dyes from the West that further contributed to decline of the woodblock tradition [6]. However, exported Japanese prints influenced Western artists, especially the Impressionists and post-Impressionists that adapted Japanese characteristics of line, colour and composition. Ultimately, the industrialization that sericulture helped to fund led to urbanization and a decline in the rural workforce. Cheap imports from China forced Japanese farmers to lower prices—making sericulture unprofitable for many of them and causing the industry to go into decline in Japan [7].
The choice of wood for the blocks was critical to the success of woodblock prints. Japanese wild mountain cherry (Prunus serrulata) was widely available and produced wood with a fine and even grain that was easy to carve and didn’t splinter [8]. Unlike Western wood engraving Japanese woodblock is cut with the grain rather than across it [8]. This made it possible to produce the fine lines seen in the print. The timber was dried for about 2 years before being cut into planks and left to season for several years. This produced a low rate of shrinkage making the wood suitable for woodblocks [8]. Seasoned timber was cut to size; planed vertically, horizontally and diagonally and smoothed using a fine whetstone to produce an almost grain-free surface for the woodblocks [8]. Other woods were used such as magnolia and boxwood; and in China, pear [8].
