Neri (Part 2)

Part 1 of this post described neri and spoke of its essential role in the sheet-forming process. Part 2 will look at some of the common mistakes that are made when referring to neri, and look specifically at how neri is prepared and used.

MISCONCEPTIONS

As mentioned in part 1, there are some common misconceptions about neri.

1) Neri is sometimes described as sticky, or a kind of glue or paste, or something that makes the fibres stick together. The material has similar properties to egg whites, or to the substance which exudes from okra, so perhaps “sticky” is not entirely inappropriate. But the use of the word sticky implies a kind of adhesive, which is not the primary or intended role of neri. Gooey, mucilaginous, viscous, or ropy are all more appropriate descriptions. Gooey is pretty spot-on, but unfortunately not especially professional-sounding. I think there are two main reasons that neri is sometimes misinterpreted as a kind of glue. First, what is now almost universally referred to as neri was historically in certain locations called nori. The fact that nori can also mean “glue” or “paste” in Japanese, has surely not helped to clarify the role of neri in the papermaking process.³ Second, while neri is not an adhesive as we normally think of them, it does in fact have the critical role of helping the fibres bond to one another on a molecular level. Scientifically, this is referred to as hydrogen bonding, which is the magic behind all papermaking. Neri is naturally hydrophilic (having a strong affinity for water), with a negative electro-chemical charge, which is also true of the fibre, leading to strong molecular bonds between the fibre, water, and neri in the papermaking vat. As water and neri are forced out of the sheet during the pressing and drying processes, the hydrophillic fibres will seek to replace those bonds they had with water/neri with bonds to other fibres. It is these thousands (millions?) of molecular bonds between fibres that hold the finished sheet together. Remember that neri is essentially absent in the finished sheet. This is key in understanding neri as a formation aid, and not an adhesive. It facilitates the hydrogen bonding process during sheet-forming, and in the end disappears.

2) Neri is occasionally introduced as a sizing agent or gum, with the purpose of preventing ink or pigment from bleeding when applied to the finished sheets. As outlined above, the presence of neri in the sheet-forming process generally leads to sheets with tighter chemical bonds and therefore a less porous surface, but it is not added to the vat with the intention of sizing the paper. For that, thepapermaker will not rely on neri, but instead will add a true sizing agent, either during or after the sheet-forming process.

CULTIVATION, SOURCES, AND VARIATIONS

Japanese papermakers most commonly derive their neri from the roots of the tororo-aoi plant. In English, the plant seems to be known by many different names, including Sunset Mallow, Sunset Hibiscus, and others. Its scientific name is Abelmoschus manihot, in the Malvaceae (or Mallows) family. Other members of this family include cotton and okra. Indeed, the seed-pods of tororo-aoi can be difficult to distinguish from okra, and okra is sometimes used by hobbyists as a substitute for tororo-aoi. Some papermakers grow their own tororo-aoi, but most use it in such large quantities that they order it from a supplier, who grows the roots specifically for the papermaking trade. She prunes back the leaves, stems, and buds of the plant during the growing season, and grows them in specially prepared, very soft soil to encourage the roots to grow as big as possible. In the fall, she harvests the roots, ties them into huge bales, and ships them to papermakers across the country. In appearance, the roots somewhat resemble ginseng roots. By far the most commonly used plant for neri is tororo-aoi, but some papermakers use nori-utsugi (hydrangea paniculata Sieb)⁴ or a combination of the two. Despite nori-utsugi’s higher price, some papermakers swear by a combination of tororo-aoi and nori-utsugi, insisting that the combination allows them their particular “shake” at the vat, which in turn enables them to produce their unique and characteristic papers. Historically, neri was also made from other plants such as ginbaiso (deinanthe bifida), binan-kazura (kazura japonica), and aogiri (firmiana platinafolia), but I have personally only come across one living papermaker trying to make and use neri made from these other plants. As one might expect, synthetic neri⁵ is also available. It is a polyacrylamide powder, and when mixed with water, it produces a mucilagenous liquid similar to that derived from tororo-aoi.⁶ Synthetic neri has its advantages, as it is not susceptible to heat, friction, or bacteria in the way that natural neri is. Additionally, the papermaker can store the powder indefinitely under the right conditions, and there are no roots to process or store. However, it does have a variety of disadvantages as well, the most serious of which is that since it is not as fragile as natural neri, it does not seem to break down and disappear in the same way. Though mostly presumed to be benign, the long-term effects of synthetic neri remaining in sheets—even in trace amounts—is still not fully understood. Synthetic neri was first developed in the 1930s and accelerated aging tests indicate no real issues, but the substance is still too new to know for sure. Sheets made in the traditional manner (including the use of naturally derived neri) have been shown to last hundreds, even a thousand years or more with little or no degradation. As a selling point, this is an advantage that most papermakers are not willing to cede. Use of synthetic neri is widespread in the Japanese machine-made papermaking world, but is still broadly frowned upon among hand-papermakers. In the end, however, even the most diligent papermaker may feel obliged to take advantage of synthetic neri’s imperviousness to temperature by adding a small amount to the vat during the most dogged days of summer, when natural neri’s efficacy and longevity are at their lowest.

PRESERVATION

Most papermakers in Japan use a solution of a preservative called Cresol [need to confirm] to preserve and store the roots, and may also use a small amount to preserve any neri that they produce. Formalin has also been used as a preservative, but its use seems to be decreasing.⁷ On rare occasions, the roots are preserved simply by drying them out, but the efficacy of the resultant neri is rather weak. The only papermaker I have met who still preserves his tororo-aoi in this way makes gampi paper. He says that since the gampi fibre is shorter in length than kozo, and naturally has a bit of its own gooeyness, the reduced efficacy of dried tororo-aoi is sufficient for his purposes. Very recently, a handful of papermakers are turning to freezing the roots without the use of chemical preservatives. The long-term energy costs of freezing large quantities of roots is not insignificant, but Cresol is also not inexpensive, and the absence of chemical preservatives in the papermaking process is another selling point the papermaker can tout.

USAGE

At the papermaking studio, the tororo-aoi roots are crushed and/or chopped and left to soak in water. The crushing is most often done by hand, with a mallet, but is occasionally completed in some kind of motor-driven stamping device. While soaking over the course of anywhere from a few hours to a few days, the roots exude their characteristic gooey substance. The resultant liquid is strained through a plastic or metal sieve (or historically through pine or cedar branches!) to remove the roots. Finally, the mucilage is filtered once again through a fine fabric before being added to the papermaking vat. Once the papermaker has prepared his neri (from whatever source), it is ready to be used to set up the vat for papermaking. After mixing the papermaking fibre thoroughly with water in the vat, neri is added. The mixing-in of neri is usually done with a bamboo pole, using long, circular, and sharp strokes. The papermaker will be careful not to mix the solution too long, as neri’s efficacy breaks down with extended manipulation. The papermaker uses his careful understanding of the desired thickness and quality of the paper being made, the base stiffness of the neri on any given day, the ambient temperature, the type and quality of the prepared fibre, and possibly other factors, to determine the amount of neri to add, as well as the length and intensity of mixing. Some papermakers know if they have added enough neri based on the sound the bamboo pole makes running through the solution. Others will scoop up a handful of solution and tip it back into the vat, observing the condition of the solution as it falls. Some papermakers (especially novices), may need to try forming a sheet to determine if the ratio is just right.

CONCLUSION

I sometimes refer to neri as “the magic ingredient” in the Japanese papermaking process. It really is what gives washi many of its unique characteristics that set it apart from western papers, such as being thin yet strong, being evenly formed, and generally free from clumps. I hope this description is helpful. Please let me know if you have any ideas or questions about neri by leaving a comment.

—Paul Denhoed

1 — Papermakers in some regions continue to use the local term amongst themselves, but will, for ease of communication, use “neri” when at a national conference, for example.

2 — It has been shown that, depending on the paper and the specific processes used to make it, trace amounts of neri may remain in the sheets.

3 — Renowned paper historian, Dard Hunter, describes the material as a paste in his book A Papermaking Pilgrimage to Japan, Korea and China. One can imagine

the papermaker explaining to the translator ‘we add “nori” to the vat,’ and the translator telling Hunter “they add paste to the vat”.

4 — Notice the re-appearance of the term nori.

5 — Synthetic neri is generally referred to in Japanese (regardless of region) as kagaku-nori (kagaku translates to scientific). Again, the term nori dies hard.

6 — I can’t watch the movie Alien without thinking of how much synthetic neri they must have used in the production.

7 — Both Cresol and Formalin are considered hazardous materials. Their use in the washi papermaking process has long been something of a dirty little secret in the industry.