Intro

More than five years ago (time flies!) I wrote a blog post about paste-making for The Book and Paper Gathering. Since then I have had a few queries about the sieving and kneading processes I described. 

In this follow-up article, I will provide information on Japanese horsehair sieves, along with background on their artisanal manufacture. I will then explain – and illustrate with photos and videos – how to best use and maintain these tools. I love using horsehair sieves because they are great for homogenising wheat starch paste, and also because they are hand-crafted. Their only downside is that, being handmade, they are rather expensive…

(1) What are horsehair sieves and who makes them?

The late 1970s saw the beginning of collaboration between East Asian and Western conservation traditions (P. Webber, 2006). Many tools, materials and techniques developed in Japan started to be used internationally, especially in paper conservation. One of these was the Japanese horsehair sieve. 

Japanese sieves are called by different names, depending on the region of manufacture, but the most common names are koshiki (漉し器) and uragoshi (裏漉し), literally meaning ‘a filtering tool’.
In Japan, they were traditionally used as cooking implements, and were only later adopted in conservation for the straining of paste and other vegetal adhesives. Conservators sometimes call them nori-koshi, ‘paste filters’. 

The density of the mesh is an important feature, as it directly influences the texture of the final product. Sieves are typically divided into those with a dense mesh (hosome/saime) and those with a looser one (arame). The sieves are also available in a range of sizes – on Kappabashi Street, a street in Tokyo famous for cooking utensil shops, I saw both a miniature sieve with a diameter of about 15 cm, and a very large one, of at least 36 cm. During my last visit to Japan, I purchased two dense-mesh sieves with a diameter of 24 cm/9.5”. They can also be procured worldwide through online conservation suppliers.

Although the horsehair sieve is the kind most commonly used in conservation, sieves can also be made from other mesh materials, such as silk and synthetic nylon fibers. Amusingly, even though I grew up in Japan, I had never encountered horsehair sieves until I began to study conservation. For everyday cooking, they have long since been replaced with cheaper plastic or metal mass-produced utensils.

Doing a bit of research online, I came across articles about a family that still practices the traditional craft of horsehair sieve making in Japan. Luckily, I was given permission to reuse their materials for this blog post (see the bibliography at the end). I have translated and synthesised the material below.

Mr Yoshio Okawa has been a craftsman of magemono (‘bent wood’, also known as magewappa in some regions) for 60 years, working in his studio in Tokyo (see Figs. 1 and 2). The studio is a family business run by Yoshio and his wife Mifuki. Magemono has been used in Japan since the Heian period (9–12^th century). While there are still many craftspeople using this bent wood technique, this studio is the last one that still produces artisanal horsehair sieves within Japan, according to Otona no sumu tabi and the other websites I consulted (in bibliography).

The last horsehair-weaving company in Japan had gone out of business many years ago, so the Okawas had to find a replacement source for meshes or learn to make the meshes themselves. Mrs Okawa went to Shikoku in southern Japan to learn the skill from elderly weavers. She then worked with a carpenter to design and build a loom. After many trials and errors over a few years, Mrs Okawa, along with her sister, was finally able to revive the skill and to produce high-quality meshes for the manufacture of sieves (see Fig. 3).

Apart from the mesh, sieve-making requires other carefully selected and prepared materials. Special skills are hidden behind every step of the assembly and manufacturing process. For example, bent hinoki cypress wood parts should be tied up to keep their curved shape, and Mr Okawa is keen to do this by traditional methods, using cherry tree bark strips instead of metal staples. These cherry bark strips are extremely difficult to procure nowadays, and have to undergo a two-month preparation process to make them flexible (see Fig. 4), which is a great deal of work.  In the same spirit, he uses only bespoke tools made by traditional craftsmen. Mr Okawa also continues to study ancient methods by repairing and reverse-engineering old sieves.

In 2021, I heard that Mr Okawa – now in his 80s – is still hard at work, and has trained an apprentice, who has now opened their own workshop. The tradition lives on! 

The key to the Okawas’ business is connection with people – learning from craftsmen of the past, collaborating with people in the present, and transferring the skills to new generations.

The whole sieve-making process used by Mr and Mrs Okawa is shown in the following video from the  Diamond Online Japan Food Heritages website – a must-watch!

Mr Okawa is kept busy thanks to the steadily increasing demand from the international conservation community. This has led me to the following thought: Can we say that conservators not only conserve objects, but also indirectly help preserve traditional craftsmanship and skills? I can think of other examples – the craft traditions of handmade papers and parchment come to mind. As modern conservators, we use 21^st-century science and contemporary ethics to guide our decisions, but at the end of the day, our work depends on a set of bespoke, hands-on skills. We need bespoke tools and authentic materials to perform our mission of caring for cultural heritage. It can be valuable to know the background of the tools and products we use, beyond what we see on the bench.

(2) With all this in mind, how do you use a sieve?

This is my approach to using a horsehair sieve. Note that it is only a guideline, and every conservator probably has or will develop their own approaches and preferences.

This video shows the processes I describe from two different angles:

a. Soaking the sieve

It is essential to soak the mesh in cold water to hydrate the horsehair, making it more supple and elastic for sieving. If you use a horsehair sieve without pre-soaking, you risk ripping the mesh at worst, or at best distending it, making it more difficult to use later on. I soak the sieve for at least 5–10 minutes before each use. Usually, I pour water into a large container until the water level is a few centimetres from the bottom. Then I place the sieve into it, mesh side down (see Fig. 6). After soaking for about a minute, the mesh becomes loose. After about five minutes, it regains tension. Once it is ready, it makes a satisfying drum sound when tapped (see 0.00–0.05 in the video).

b. Putting the paste on the mesh (see video at 0:07 and 4:55)

After soaking, gently remove excess water from the sieve with a cotton cloth or something similar (video 0.07–0.12 and 4.55–5.00). Then put a small handful of cooled paste into the centre of the mesh. Try to use only the central area of the mesh, which has the most elasticity and is easiest to clean. Paste stuck to the circumference of the sieve between the mesh and wood is difficult to remove!

Why do I recommend using cooled paste?  Not because hot paste would damage the horsehair mesh – the mesh is actually quite heat-resistant. However, I have found that hot paste hasn’t fully gelled yet, which makes it less suitable for sieving and kneading.

c. Kneading  (see video at 0:15, 2:38, 3:34, 5:10, 6:53, and 8:10)

I learned from Japanese conservators that the kneading process helps homogenise the paste before sieving. This is done by moving a spatula in a circular motion on top of the paste and occasionally tapping the paste lightly. The motions should be light and regular. The objective is to knead the paste on the surface of the mesh, not to push it through. You will notice a change of texture after going around the circle 20 to 30 times. I check the elasticity of the paste by lifting the spatula, as seen in the video.

For both kneading and sieving, I use a bamboo rice spatula/paddle (shamoji), which you can find in most East Asian markets. It has a wide flat back, which makes it easy to manipulate the paste.
The rice paddle can be dampened before use to keep paste from sticking to it.

d. Sieving (see video at 1:45 and 6:10)

After kneading, the paste is very gradually sieved. The most efficient way of sieving is to position the sieve so that the weave of the mesh is at about a 45-degree angle from where you are (see Fig. 7), then to pull the spatula towards you while pressing on the paste. I sometimes rotate the sieve while working, but I always make sure that the weave is at a 45-degree angle to me. Don’t hesitate to put a fair amount of pressure on the sieve to force the paste through – but of course don’t break it! If the horsehair mesh is properly hydrated, it should have nice elastic resistance. If you feel that the mesh’s tension is weak, it may need longer pre-soaking.

e. Collect the paste, then repeat steps c and d! (See video 2:10–2:35)

Flip the sieve over and scoop the paste from the reverse side of the mesh. I bring the paste towards the centre of the sieve. Then, by moving the shamoji in a circle, I make a compact shape like a  mochi (Japanese rice cake).

I repeat steps c through e a couple more times until the paste is homogeneous and elastic. In the video, you can see how much the texture changes between the repetitions. Compare how it looks before sieving (5:03–5:10) and after sieving (9:30–9:50). This means that you can control the elasticity of the paste, depending on the intended use. Even grainy, stiff or somewhat old paste (for example, one that has been kept in the fridge for a week) can be given a second life by careful sieving.

Cleaning and storage

Always wash the sieve thoroughly after each use. Be sure to remove all traces of paste, including those that might be hard to see. Rotating the mesh under a light source makes the paste residues easier to see (see Fig. 8). I would avoid using a stiff brush on the mesh, because this may damage it; use either your hands, a soft sponge with light pressure, or your faucet’s shower mode to clean between the hairs (see Fig. 9). I use only cold or lukewarm water, below body temperature, without any detergents. Detergents should not be necessary because water washes paste out well enough. If paste is stuck to the wooden frame, cleaning can be a bit more aggressive; for this I use a tawashi, a vegetable scrubber.

For storage, keep out of direct sunlight, extreme temperatures and extreme RH to avoid cracks, wood rot and mould damage. Best to store the sieve in a well-ventilated area on a rack or hanging from a wall. 

If properly taken care of, a well-made sieve can last decades… I heard that if you are in Japan, Mr and Mrs Okawa can repair your damaged meshes – one day I would like to try this service!

Special thanks

Special thanks to Mr Yoshimasa Tanemura from the Ichii company for his great help with putting me in touch with the  Okawas and for allowing me to use pictures from the Otona no sumu tabi website. Thank you to Mr and Mrs Okawa for their kindness and for graciously allowing me to write about them in this blog. Finally, I am grateful to The Gathering team for their patience and for providing me with an opportunity to write on this subject!

Thanks to you too for reading this post. Feel free to email me at mm2286@corpus.cam.ac.uk, and if you have any comments, please leave them below.

References

Pauline Webber (2006) ‘East and West: A unified approach to paper conservation’, The Paper Conservator, 30:1, 43–56

The information and images are from

Otona no sumu tabi website (2017)  https://sumutabi.net/1069, https://sumutabi.net/1070 and  https://sumutabi.net/1071, all in Japanese 

Monoshoku.jp website (2019) https://monoshoku.jp/introduction/1324/  in Japanese. 

Diamond Online Japan Food Heritages website  https://vimeopro.com/motokiyo/explore-for-japan-food-heritages/video/75647588

(all websites accessed on 8th Jan 2022)

Mito Matsumaru is currently a book conservator at the Cambridge Colleges’ Conservation Consortium, UK. She has received an MA in the Conservation of Books and Library Materials with distinction at West Dean College, UK, in 2017. She holds a BA in Art History (2012) and a Master in Conservation Science (2015) from Tokyo University of the Arts, Japan. She has received several awards during and after her studies, and has gained field experience in both Japan and the UK, including at the Victoria and Albert Museum and the Wellcome Collection.  

Mito’s MA research on wheat starch paste, published in 2021, includes a comparative study of how sieving affects paste quality. It can be accessed at https://www.tandfonline.com/doi/full/10.1080/19455224.2020.1864747.