The Shibui Kibo Prototype: A Copper Behemoth

The first thing that strikes you about this pen is its beauty and closely associated with that: the colour and texture. The second thing is its weight. The former is the product of the skill of an urushi lacquer expert: Ruth Bolton, who has been developing her skills over almost two decades in Japan and latterly in the north east of England. The latter characteristic of the pen’s heft results from a massive piece of copper bar lathed into a fantastic prototype pen by this talented pen maker. But first let us consider lacquer.

Layers of Lacquer

Varnishing and lacquering techniques have been around for a very long time, typically being used to protect precious or perishable surfaces from the elements or human touch. Talk to a conservationist about varnish and lacquer they will likely grimace for it is tough stuff commanding time and deep respect to deal with. Lacquer of the Chinese and Japanese variety very definitely demand respect as it is a technique and skill developed and refined over thousands of years. It is also perhaps the ultimate slow craft and art.

Lacquering originated as a Chinese varnish technique over 3,000 years ago but is now archetypically synonymous with Japanese lacquering. The latter uses the sap of the urushi tree, often referred to as the lacquer tree, or the Japanese varnish tree (botanically: Rhus vernacifera). The Japanese lacquer: Urushi, is carefully tapped from the tree for the raw sap is toxic to the touch, as are its fumes. So, it is inherently dangerous collecting the raw material, processing it and using it to lacquer. However, the risks and the skills of making and using the lacquer have been around for many thousands of years and Chinese, Japanese and Korean crafts men and women have perfected the know-how to make it a tradition of high-art finishes on craft objects: furniture, bowls, wooden caskets, metal and in the last hundred years on pens.

The raw lacquer is a viscous greyish-white and is taken only in limited quantities and times from mature trees that are at least ten-year old. The processes of tapping the trees for the urushi sap and processing it into a high-quality lacquer require great care and are very labour intensive. Using urushi is even more labour intensive as the active ingredient of the urishol oil needs to enzymatically transform under carefully controlled conditions of heat and humidity (which activate the naturally occurring catalyst laccase, a multi-copper oxidase in the urushi oil – more on copper later) into a hardened polymer-like coat. The dried coat is inert and non-toxic. Typically, a urushi lacquered object will have some 50 coats in a series of stages, all very carefully applied and then allowed to slowly dry over long periods (at least 24 hours) in a humidor where the humidity is at least 40% and temperature are maintained at between 15-35o Celsius. (Higher humidity, such as say 90% will greatly accelerate the curing process. Similarly, the higher the temperature the faster the curing.) Faster drying will result in darkening of the cure layers. The typical steps in the layer process are as follows:

  • Kiji: the base layer coating (3-4 layers)
  • Nakanuri:  the intermediate layers (10-15)
  • Kawari nuri: decorative texturing where gold powder or other additives are sprinkled or carefully positioned on the surface before further urushi layers, (5-10 layers);
  • Shuai urushi: the penultimate layers (10-15); and
  • Kijome: the final finishing layers (5-10).

The final stages include further charcoal-polishing and rubbing with a very fine abrasive often made from powdered horn applied with a cloth moistened with urushi. This is serious craftwork commitment and one that Ruth Bolton has used on previous fountain pen projects using Japanese ebonite.

There are, as you might expect variations on this layering process and Ruth Bolton has used another urushi technique which involves accelerating the drying process via baking the layer onto the copper pen.

Thus, the Shibui Kibo model reviewed here differs from the typical urushi lacquering steps above in that the metal allows another curing process to be added to the mix: Yaketsuki, in which the urushi lacquered product is cured in an oven. Ruth has spent many years in Japan and can speak and read the language which has allowed her to continue her urushi research and learning. In the Yaketsuki technique temperature and duration varies according to the metal of the object. In essence dependent on the metal composition the Yaketsuki technique allows the curing and finishing to be completed in a day as opposed to the many days and months typically required in urushi lacquering. However, the resultant finish with Yaketsuki is a much more, glossy look than air cured urushi. There is also a loss of some of the colour in the oven cured process. But now let us consider copper.


I like copper* and it is an interesting material for a fountain pen, particularly in the age of Covid-19, where its inherent anti-bacterial and anti-viral properties take on a new relevance**. My Periodic Table Pro app tells me that this atomic number 29 element has a density of 8.92 g/m3, Mohs hardness 3***, Vickers Hardness 343-369****. Translated into pen world vernacular this makes it an inherently heavy pen gram-for-gram against, for example, a stainless steel Kaweco Supra (13% heavier), or a Gravitas aluminium bronze (15% heavier) but relatively softer scratch and impact wise; indeed, on a par with aluminium. It is worth noting that aluminium is a much lighter metal: 30% of the comparable weight of the same pen in copper.

There are various other copper fountain pens around; for example, Kaweco’s Liliput Fountain Pen in Copper, Ensso ES, and the Ystudio Classic desk fountain pens to note a few. American metal pen specialist Karas have Kustoms Ink Copper in several model versions. And almost finally, there is of course UK’s Namisu, which has also had a version of its Nova in copper. A copper pen will scratch fairly easily and tarnish over time. So, perhaps this is not a typical go-to material for pen makers to use; therefore, it tends to stand out when pens are made from it. And the Shibui Kibo Prototype certainly stands out and some more.  

Measuring Up

The usual comparison tests show the Shibui Kibo Prototype measuring up quite well against its metallic peers, as seen in the table below.

PenLengthWidthWeight Uncapped
Shibui Kibo prototype141.1015139.37101.62
Gravitas bronze147.661597.1570.70
Lamy Al-Star1391521.7012.20
Diplomat Aero1401541.6337.00
(Note: all measurements are my own so give or take calibration errors they may vary with the ‘official’ scores for the pens.)

The different parts of the pen feel good if unusually heavy. The section length is, at just short of 30mm (to the end of the threads) generous and the urushi finish on it gives it a great tactility. I found that the threads did not intrude on my grip. The barrel is a reasonably typical 84.12 mm so it looks and feels well-proportioned. Indeed, proportion wise it is almost quite standard in many ways. And as you can see from the pictures this is a classic cigar-shaped fountain pen. At the business end there is a Bock #6 nib in red to match the pen. It appears to be a fine nib and it works reasonably well but with the Monteverde ink and this pen I would love to have it tuned to bleed and gush a bit more across the page.

What does it feel like, write like? Well, it feels stout and strong nestled into the crook of the hand; as squat and snug as Seamus Heaney’s pen. Hands are complex things as I have come to discover from having Trigger Finger in both hands as well as Dupuytren’s contracture. Notwithstanding that the Copper Behemoth did not present problems holding it for sustained periods. Typically, when testing a pen I will write a letter, or two with it which tend to be 8 sides of A5 with a fine, or extra fine nib on 7mm feint lined paper. I wrote two letters with this pen and it did not leave my hand, wrist or forearm unduly tired. The texturing of the urushi on the section probably helped to maintain a relaxed grip and I found it easy to smoothly guide and glide the pen across the page.

The pen came with a small international size cartridge filled with an excellent complement of Diamine Ancient Copper. On exhausting it I placed a converter in the pen and filled it with an equally appropriate Monteverde Copper Noir. I carried out some writing on 80 gsm, 90 gsm and 100 gsm paper and the pen worked a treat. Pictures of some writing samples are attached. It being the 80th birthday of Bob Dylan I copied out some lines from his songs.

It is a prototype so there were some areas where refinements could be and surely will be made: where the section meets the body, the space for a cartridge or converter is a bit tight in length, and the weight of the body could probably be reduced by taking some more metal off (it is 3.2mm in thickness on this prototype model). Whilst not personally put off by the weight I think that reducing the overall weight might make it more acceptable and attractive to a wider range of pen folk.     

The Kibo model will be available in copper, brass, and aluminum. The copper and other Kibo models are intended to be heavy and robust. For those folk over-worried by weight the aluminium version will take 70% off the weight. Ruth plans to release lighter models in the future.

Her initial offerings will be via a Kickstarter campaign launched at the beginning of June 2021. The details can be found here: –

Ruth Bolton is a talented pen maker and very skilled urushi lacquerist. Her work will definitely generate great interest and desire to have one of her pens in your collection. She is a talent to watch and it is really exciting to have had the chance to review this pen. We pen folk struggle with our acquisitive urges and this is one that you will find hard to resist.

Finally, a question for UK pendom: is she the first UK female fountain pen maker? If she is, then certainly another good reason to celebrate her fabulous pen.

In conclusion

There are two things that I like about this pen: it’s beautiful finish and tactility and the material that it is made of: copper. The latter provides an excellent canvas for Ruth Bolton’s specialist urushi techniques and this pen is very different from anything that I have used. It really is a stunning pen to look at and to feel in the hand. Ultimately the prototype pen reviewed is also the heaviest by a country-mile; my brawny bronze beast of the Gravitas has to yield its place to the gravity pull of this beauty.

For me the Copper Behemoth of the Shibui Kibo prototype initially struck me as a bit too heavy but it certainly proved not a problem to write with for sustained periods. You would probably keep it as a desk pen delighting in its beauty and marvelling at its texture and colours. Whilst it is very strong and robust you would probably not take it out and about as an Every Day Carry. I will avoid paltry puns about big splashes, etc but Ruth Bolton has certainly pitched a substantial and momentous pen at the community and like many others I think she will be a name to watch and follow amongst bespoke pen makers. And like me I think that you will definitely want one of her pens.


The pen reviewed was loaned by Ruth Bolton for review purposes to United Inkdom reviewers. There is no association or affiliation with the maker and this review is independent and provided without fee or favour.


*As an economic development officer I spent some time working with an Italian copper wire manufacturer helping them to expand and with several successful grant applications, one of which should have brought a recycled copper smelting plant to West Yorkshire. The latter project would have produced the copper bars that Ruth Bolton uses to make her pens. Paradoxically electricity supply, or its costs more precisely, killed the bigger project.

On the anti-bacterial and anti-viral properties of copper there is a really interesting piece in the Smithsonian Magazine which is always great. Check it out here:

***Mohs hardness is a relative or qualitative ratio used to measure the hardness of minerals, where diamonds are the hardest at 10 and talc the softest at 1. It is essentially a scratch resistance scale. Your mobile phone’s Gorilla glass will typically have a Mohs hardness of 6. So, your phone could end up scratching your copper or aluminium fountain pen.

****Vickers hardness is an impact test where a sample of the material’s resistance is gauged from the impact of a micro diamond indenter. It is a widely used hardness test and the square diamond pyramid shape of the indenter is echoed in the measure: Vickers Pyramid Number (HV) or Diamond Pyramid Hardness (DPH). The size of the indentation on the material tested indicates the hardness; a small indentation mark means it is a hard one. Obviously the measurement is more precise, with the surface area and depth of the indentation calculated to provide the hardness measurement.

Published by mickmckigney

I am an Irishman living in West Yorkshire. I have been using fountain pens for about 50 years but in the last five have increased my collection of pens, ink and paper. I am also interested in bookbinding and leatherwork.

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