Tag Archives: hera

Heat Treated Tonkin Bamboo Hera Blanks for Sale

Tonkin Bamboo. Note the large areas of black power fibers. Compare this to the endgrain of a chopstick.

Hera are small Japanese tools useful for a variety of scraping, lifting, and delaminating tasks. They are common in paper conservation. Tonkin is a dense, flexible and strong type of bamboo that handmade fishing rods are made from. More about Tonkin.  Heat treating increases the elasticity of the bamboo.

Even so, hera with very thin and flexible tips can wear and can crack, so they need to be maintained by sanding, carving, reducing the width, or even shortening.  Once you have the skills to make a hera, they are easy to maintain. If you want to keep things simple, shape it with your Olfa knife, sand it with 220 grit, then finish it with 600 grit.  More tips on shaping bamboo.

These blanks are roughly 6 inches long, and 1/4 – 3/8 inch wide.  If you want to make two narrow hera, you could split a wider blank.  Just ask me for the widest one I have. Making your own tools to the exact size and shape you need is rewarding and satisfying.

Purchase heat treated Tonkin hera blanks here, only $10.00/ each!

Top, bottom, and side views of a typical blank.

A finished hera. This is not difficult to do, but takes a bit of time.

Heat Treated Tonkin Hera

Tonkin

I’ve done some research and ramped up the quality of the bamboo I use to make hera.

First I have decided to use Tonkin, a super strong and resilient bamboo which is used by bamboo fly fishing rod makers. As evident in the image above, it has a preponderance of dark “power fibers”, which give it strength and a pleasing density.  Look at the end of a chopstick for comparison, which is generally pure white weak pith. There are over 1,000 species of bamboo.

I’ve also decided to heat treat the bamboo after initial shaping.  Dr. Wolfram Schott has a fantastic paper, Bamboo in the Laboratory, if you are interested in more details. His Bamboo under the Microscope is also highly recommended. Both breaking strength and modulus of elasticity increases according to his research and tradition in rod making. I’m not totally convinced it makes a difference for such small tools, but it certainly doesn’t seem to hurt. And the stove adds a comfortable warmth on these increasingly cold fall days!

Heat treated Tonkin Hera for sale, $25

 

New Hera

Hera

Hera are Japanese bamboo spatulas.  There  can be made in a wide variety of sizes for numerous purposes; lifting, stirring, folding, smoothing, mechanical removal of backing material, marking for wet tearing, etc….  They are typically owner made, and can easily be customized with a knife or chisel– ie. making the blade slightly more flexible (by thinning) or less flexible (by shortening), making it smaller to fit a specific purpose, and making it sharper or duller.  In fact, since the edge is very delicate, it is almost necessary that the owner be able to repair or reshape them.  Recently, I became interested in them thanks to Robert Minte, conservator at the Bodeleian Library in Oxford, UK, who showed me some examples he made when he was studying scroll mounting in Japan.

Fig. I.  Examples of several hera I have made.

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Fig. II.  Close up of a single hera, showing the flexible curved blade, transition from the handle, and the typical placement of a growth node near the end of the handle, on the right.

 

Hera are quite easy to make and another useful tool in a conservators arsenal. Small, thin ones as pictured above are useful for backing removal. I’ve even used some stout ones for lifting weak, deteriorated book cloth. Some conservators find them useful when removing pressure sensitive tape.  Thicker pieces, with more of a knife shape, after soaking in water, are an effective tool for wet tearing, since they slightly abrade the tissue as well as wetting it. The strength, flexibility, and smoothness of bamboo is unique among materials.  They are also very fun and highly addictive to make.

Bamboo.  I found some bamboo at a local hardware store/ garden center.  Larger diameter bamboo permits making a wider tool- a 3 inch diameter piece yields about a maximum .5 inch wide tool. There are over 1200 kinds of bamboo, but traditionally the best for hera is susu dake, or soot bamboo, which is very hard.  According to Thompson, “Soot bamboo is so called because it was reclaimed from the roof beams of old Japanese houses.  Other bamboos are perfectly acceptable but the slower grown (the hearly growth nodes should be as close together as possible) will produce more durable tools as the structure of the wood is more compact.” (1)

I cut the bamboo to the desired length with a coping saw.  It is best to cut the pieces longer than required, then adjust the length after preliminary shaping.  After cutting to length, it is easy to split into desired widths with chisel, then to pare them into rough square of rectangular shapes.

Fig. III. Splitting the bamboo with a chisel.

Working on a small block of wood to protect one’s work surface, the chisel was then used to square up the sides to the desired width, clean off any of the thin, soft inner lining of the bamboo, and smooth any rough corners.  Mainly the soft interior of the bamboo is shaped– the cutting edge (the outside of the tool) is the outside of the bamboo.

To shape the blade, I found it easiest to clamp the handle of the tool and working with the bevel of the chisel, gradually shape a graceful transition.  Bamboo is very easy to split and shape.

 

Fig. IV. Shaping the blade

Once the blade is at the desired thickness, it can be chopped to length with a quick chisel blow.  At this point the bamboo is fairly brittle (2) so it is safest to continue to shape and refine the edge with sandpaper or scrape it.  Caution: as it gets thinner, it can get sharp enough to easily puncture flesh. A progression of 150 US grit followed by 400 US grit worked well for the initial shaping.  Final polishing consisted of a using 3M Tri-M-Ite  polishing paper of 1200 then 6000 grit.  A thin coat of Renaissance wax gave it a nice look and  feel.

(1) Thompson, Andrew.  ‘Japanese tools for conservation’ in The Paper Conservator, Vol. 30, 2006. (Pp. 65-72)  There is a picture of a variety of sizes and shapes of hera in the article.

(2) In fact, it occurred to me that bamboo is much like the structure of a Japanese chisel– there is an extremely hard cutting edge (the outside of the bamboo), supported by a softer backing material (the inner pith) that adds flexibility and strength.