On Tool Embodiment

Hand tools are paradoxical objects. They are collected, admired, displayed, bragged about, hoarded, treasured for their provenance, valued for their aesthetics, appreciated for their functionality, and more. In short, we endow them with all kinds of meaning as things. But when we are using them, they disappear from our consciousness and become extensions of our hand which we manipulate as naturally and as walking. They become embodied, an extension of our body, a seemingly natural part of us. Philosopher Don Idhe clearly explains the concept using the example of driving a car: once we know how to do it, our hands naturally steer to keep us on the road without conscious thought. In embodiment, we don’t really notice tools or think about them: we think through them, they become extensions of our hands. 

Can some of the largely subconscious, complex decision making processes and hand actions during embodiment be described?  What really goes on in an embodied state? Could it be reconstructed, or at least some the complexities described retrospectively? Towards these ends, I will narrate (like a homunculi in my head) some of the decisions and actions that become take place during the embodied activity of paring leather.

Fig. 1. My M2 hybrid leather parking knife, made by stock reduction from a machine hacksaw blade.


One aspect of leather bookbinding which differs from binding in cloth or paper, is the three dimensional nature of leather, which needs to be pared (aka. skived) to different thicknesses. For a fully covered binding, the leather at the spine and headcap area of a book must be gradually beveled and the turn-ins (the area where the leather wraps around the edge of the boards), must be thinned, as well as the spine of the book. There are a number of tools that can be used to do this: differently shaped paring knives, double edge razor blade paring machines, modified spokeshaves, and even sandpaper. I will confine this description to using one specialized tool: an M2 hybrid leather paring knife, which, full disclosure, I designed, make, and sell. Paring leather in preparation for covering a book is representative of a deeply embodied skill: it looks easy and natural when someone else does it, but when you try it for the first time….

Fig. 2. The board edges and headcap of a leather binding formed from thinly pared goatskin leather.

Embodiment in tool use doesn’t just happen. Fluency with the craft skills to manipulate the tool are a prerequisite. But once these skills are acquired, embodiment is a key component in what makes craft relaxing and freeing. It is an escape from the relentless quantification of our 21st century existence. The maker does not have to consciously thinking about hand movements, hand placement, the action of the knife, the woes of the world, or what to eat for dinner: they get out of their head a for a bit. A deep and intuitive connection to the material develops.

Embodiment is difficult to describe in words, which may be why craft education traditionally involves close visual and physical contact with a skilled practitioner, such as in an apprenticeship or trade school, rather than written manuals. At least in the history of bookbinding, most manuals pre-nineteenth century were written by outsiders describing the field, not the binders themselves. Diderot bemoaned the inarticulate nature of the craftsmen he interviewed for his Encyclopedié, but it may be more of a reflection of how craft skills are learned and expressed than a linguistic shortcoming on the workers part. Learning to use a new tool is often referred to as “getting a feel” for it, implying it is something not easily expressed through words or textual description.  


In addition to learning how to manipulate the knife, success depends on preparation of the leather and the sharpening of the blade. Although the verbs “pare” and “prepare” come from different French and Latin root words, the somewhat rusty poetic areas of my mind envision a close literal relationship between the two. Pre-paring is getting ready for the paring. 

Fig. 3. An entire goatskin and the frame to identify the book area. The neck is on the right, the spine in the middle, and the four legs splayed out at the corners.

Once a specially vegetable tanned goatskin for bookbinding is obtained, a frame much like a window mat is made in order to pick out the optimal area. An entire goat’s skin is purchased, not a cut out rectangle. Each skin is different: all have unique scars, stretch marks, and grain patterns. It would be irresponsible, wasteful, perhaps even unethical to not respect the animal by using it in the most efficient and aesthetically pleasing manner. Usually the spine of the animal is aligned with the spine of the book, for the pragmatic reason that goats often run into a branch or fence, so there are often scars on the spine. Once the area for the book is chosen then carefully cut out, the next step is boarding. 

Boarding involves rubbing the skin folded back on itself, grain side to grain side. The grain side is the “outside” of the skin, the flesh side is where it was removed from the animal. Boarding evens out irregularities in skin, making it easier to pare and manipulate during covering. Historically it was done with cork faced boards — hence the name — today it is a more intimate process, usually done by hand. 

Fig. 4. Boarding the leather before paring, evening out irregularities with my fingers.

I constantly feel the skin with the length of all my fingers, working out inflexible areas within the skin. This process also gives me time to analyze the skin’s consistency. All four directions of the leather are boarded: top to bottom, side to side, corner to corner to corner, and the opposing corners. I do this gradually, slowly working out hard areas, until the entire skin is as relaxed and evenly flexible as possible. It’s like I’m giving the skin a massage.


Once the leather is prepared, the paring knife needs to be checked and more often than not, resharpened. Given the abrasiveness of leather coupled with its stretchiness, a paring knife needs to be exponentially sharp. Sharpening is an ur-skill for many crafts, and after the hammer likely the most basic human tool. Sharpening simply means using a grit progression of smaller abrasives, to achieve a finer edge on the knife. It is performed freehand in bookbinding, due in part to the handles most bookbinders have on their knives, making itimpossible to mount them in a jig. I also find it is quicker and easier to sharpen freehand. The hand skills necessary for sharpening freehand mutually reinforce the hand skills necessary for paring. Like boarding the leather, it is a meditative, repetitive, and essential.

Fig. 5. Sharpening on a 15 micron film. Note the small black particles floating on the water, which are 15 micron sized pieces of metal.

I carefully place the knife on the wet abrasive film, watching the way the water squirts out of the sides to be sure it is flat and making contact. I use abrasive films, but the technique is the same with oil stones, water stones, diamond stones, ceramic water stones, or whatever. Most sharpening surfaces are particles of aluminum oxide, silicone carbide, or diamond bonded in a matrix or on a backing. It tears valleys into the steel, the shape of the particles. The smaller the particles, the smaller the valleys in the steel, and the smoother the resulting cutting edge will be. I start with a coarse grit to flatten the back, working edge to edge. Pressure starts out light, making sure the knife is in precise contact with the film, then heavier once the position is set, then light again, so the scratches don’t penetrate as deeply. Black metal particles, called swarth, are removed from the blade. A 40 micron abrasive removes 40 micron sized swarth, creating 40 micron scratch valleys in the blade. The swarth floats on the water which lubricates the film, preventing the metal from glazing the surface. Heavier pressure abrades more, lighter pressure less. Even minute changes in the pressure can effect where the knife is abraded. I listen for the sound of the knife on the grit, letting me know I am making firm consistent contact. Back and forth, edge to edge, moving my body not my hands to keep the knife flat. I can’t see what I am doing: so how do I know it is done?  I continually feel for the burr, which is a wire thin piece of metal that overhangs the point where the bevel and the back of the blade meet. There is no other easy way to know when these planes meet, except to exceed it. One of William Blake’s “Proverbs of Hell” often comes to mind, “You never know what is enough unless you know what is more than enough.” 

Fig. 6. A diagram of the burr. If it is made with a coarse grit, it can be felt, but usually it is too small to see.

Once I feel the burr, I flip the knife over and work on the bevel. I keep doing this until the burr is flipped over to the back side once again, then switch to a smaller grit. I try to use the entire surface of the film to keep it wearing evenly. I watch the swarth. These marks give me an idea where I am wearing the metal on the knife. I keep feeling for the burr on the back: once I feel it from the tip to the heel of the blade, I flip the knife again to the bevel. I keep repeating this, finishing with a one micron. A typical hair on your head is about 40 microns in diameter.  I stand at my workbench, keep my arms rigid but relaxed, and move my upper body to apply pressure, swaying back and forth. My hands would tire quickly if I were seated. The back and the bevel must be kept absolutely flat on the film. Changing just one degree would make the blade more obtuse, and not as sharp. When I am done with my grit progression, I strop the knife.

Fig. 7. Stropping on a piece of horsebutt leather, with green .5 micron chromium oxide honing compound. On the left, the compound is clean. On the right, metal particles have turned the compound black. 

Stropping is a different movement — think of an old time barber with his straight razor — the knife is pulled away from the cutting edge in a perpendicular orientation. Once again, it must be held exactly to the established angles, or all the hard work in the sharpening can be ruined. The visual clues while stropping are the black bits of metal embedded in the bright green chromium oxide compound. I usually count in my head, 20 strokes on the back, then 20 on the bevel. Stropping too much on one side can cause the knife to cut unevenly. Finally, I strop it with a .25 micron diamond paste. The finest — think microscopically smooth — edge will be the sharpest and longest lasting. When I’m done, I can see a reflection of myself in the blade, perhaps a literal visual indication embodiment: I am in the tool, it is a part of me.

Fig. 8. Beginning edge paring, making an angled cut to the edge.


Once the leather is boarded and the knife is ready, paring begins. Each skin is essentially unique and reacts differently to the knife. What will this skin be like? These differences keep craft interesting. A sharp knife glides into the leather so effortlessly it is frightening. Many people actually scream, or maybe more accurately emit a little yelp, partially due to fear, partially gratification that their knife cuts so well after a long sharpening process. When carving wood, it usually has a grain, there is differeing amounts of resistance to the knife in various directions. When paring leather, a sharp knife moves without resistance in any direction. 

Bookbinder Tom Conroy has likened paring to flying an airplane, with the three dimensional considerations of pitch, yaw, and roll.  The knife can cut so quickly, it goes through the leather, crashing into the paring stone, dulling it or worse, chipping the cutting edge. Then it needs to be sharpened again. Lessons learned the hard way are rarely forgotten. Over time, all the aspects of paring — the angle of the knife, the angle of the blade, a sense of the sharpness, the amount of skin that can be cut into, and the required pressure — become embodied. This is when it gets fun.

Fig. 9. Continuing edge paring with a second strip, deeper into the leather.

Paring becomes automatic, or second nature. No consciousness interferes. I think through the knife right to the cutting edge, gliding up, down through the thickness of the skin. Holding the knife and cutting is as natural as typing these words: no attention is paid to my hands, but my thoughts seem to appear in words on the screen. When I think about the range of subtle hand motions to control the knife, there are hundreds of minute differences to control the knife. Pressing harder on a corner of the knife causes it to dig in and remove more. Pressing down on the entire cutting edge will cause it to run a little deeper. Angling the knife — even slightly — changes the effective blade angle, and therefore the sharpness. I feel like I am surfing through the skin. Altering the angle a few tenths of a degree changes everything. Even the words I’ve chosen to describe this — flying, gliding, surfing — indicate the freedom that happens in embodied craft work. I suppose it is much the same as Csikszentmihalyi’s conception of “flow”, or what is called “the zone” in sports.

Fig. 10. Paring a third strip deeper into the skin. 

It’s an oversimplification to just consider what the knife is doing. My other hand is also entirely engaged: changing position, smoothing the leather, preventing it from stretching oddly or bunching up, in harmony and response to the direction and pressure of the knife. Sometimes the fingers hold the skin, sometimes the palm. Posture matters: hardly any bookbinding can be done while seated.

Fig. 11. And yet more paring, this time perpendicular to the edge of the leather, with a scraping action. Note the small bits of leather, rather than long strips, being removed.

Once again, a rhythm develops, part of the relaxing reward of craft. I edge pare one side of the skin, go back and pare it deeper, then go back a third time or even more.  Continually feeling the skin thickness and watching the dye color change serve as a depth indicators. Like many materials, leather likes to be removed in long slicing strokes if possible: it makes for less work later on, since the pared area is largely even. Finally a perpendicular scraping motion is employed to give the skin a final smoothing.  I’m constantly checking the reverse side of the skin for previously pared bits that can cause the knife to make a hole in the skin. 

Fig. 12. [CAPTION] Almost done, the skin is pared so thin that some of the grain of the leather is cut through.

Paring is not a strictly linear process; it is a natural one, a back and forth between paring and stropping, checking the leather thickness, resharpening the knife if necessary, then, paring and stropping some more. Scraping more leather and checking again. The closer I come to the desired thickness reveals a cruel irony: simultaneously the leather becomes thinner and weaker, while the knife becomes duller from use. Both these factors can cause the leather to tear. Feeling the leather, folding it over on itself to double the thickness and thereby doubling the irregularities is crucial. I strop the knife more and more often and grip it tighter.

At this stage, embodiment becomes fragmentary, conscious thoughts continually break through, interrupting the flow. A final scraping is a tightrope of sorts: can I make the leather a little thinner, neater, and a little more even?  Will this tiny ridge in the leather show on the final product?  Is it as good as I can make it? Am I finished paring? A preconception of perfection — rather than paying attention to the materials at hand — can spell disaster and regrets for not stopping earlier. Craft questions usually don’t have a straightforward yes or no answer; more commonly is the unsatisfying — it depends —  which lies somewhere on a continuum between an experience-based Gestalt and a guess.

Fig. 13.  Demonstrating paring a small piece of leather in real time.


Mihaly Csikszentmihalyi. Flow: The Psychology of Optimal Experience. New York: Harper and Row, 1990.  Detailed breakdown of his concept of “flow”, which is closely related to embodiment.

David Esterly. The Lost Carving: A Journey to the Heart of Making. New York: Viking Penguin, 2013. Wonderful first person poetic narrative describing wood carving.

Don Ihde. Technology and the Lifeworld, from Garden to Earth (Bloomington and Indianapolis: Indiana University Press, 1990).  Essential theory and very readable. A post-phenomenological theory of embodiment.

Jeff Peachey. “Thinking About Making: You, Artifact and Tool”. Blogpost October 6, 2015. https://jeffpeachey.com/2015/10/06/thinking-about-using-tools/   Contains an overview of other factors when using tools.

Jeff Peachey. “Conservation and Tools: An Inquiry into Nature and Meaning” The Bonefolder, 1, no. 1. (2004): 19-21. http://www.philobiblon.com/bonefolder/vol1no1contents.htm  Explores tool use in the conservation of historic artifacts.

Jonathan Ashley-Smith. “Losing the edge: the risk of a decline in practical conservation skills.” Journal of the Institute of Conservation. Volume 39, 2016, Issue 2. 119-132.

https://www.tandfonline.com/doi/full/10.1080/19455224.2016.1210015  Insightful analysis of hand skills, why they matter, and how they can be taught.


Jeff Peachey is a tool maker and book conservator based in New York City. When he is not embodied in work, he writes, lectures and teaches bookbinding and toolmaking workshops internationally. His forthcoming publication in Suave Mechanicals 8 is “The Binder’s Curse”. It analyzes the insane bookbinding poetry of John Bradford’s 1815 The Knight of the Folding Stick in the broader context of early 19th century bookbinding practice. 

Books: jeffpeachey.com  
Tools: peacheytools.com  
Instagram: @jeffpeachey

“The life so short, the craft so long to learn.”
― Hippocrates