Category Archives: book conservation

A Guide to Swell

In bookbinding, the term “swell” describes the thicker area of a book block at the spine due to the addition of sewing thread. It depends on factors detailed below, but a binder or conservator generally does not have control over all these variables. Knowing how to estimate the amount of swell that will develop is one of the most important aspects when planning to sew a book, since it corrolates to the degree of round and the shape of the shoulders that a book will end up with.

Different binding styles need different amounts of swell. Too much swell creates a textblock that is unstable, squiggly, and difficult to back. Too little swell and there are insufficent shoulders which are necessary for some styles of binding. In all case binding structures, there is more leeway with amount of swell, and as long as it is not excessive it will be sucessful; with bound books the tolerances are much tighter. For example, if you are resewing an existing text block it is critical the new shoulders exactly fit the original boards.

Softer, multi-ply threads afford much more control of swell while sewing as compared to a hard modern thread. Currently, I primarily use threads sold by Colophon Book Arts, including the Colophon Best Blake Thread and the Londonderry Linen Lacing Cord #4. Both can be deplyed if desired to make them thinner. I also prefer to support smaller, specialist bookbinding supply companies. If you are using standard threads, 25/3  is a reasonable starting place. 

Many early binding structures—even up to the late 18th century—manipulate the shape of the boards to fit the spine, rather than the modern fine binding tendency to fit the boards to a 90 degree shoulder.  This makes it easier to fit a wider range of boards to a given swell. Obviously, this is not an option for many binding structures.

There is no formula, instead these ten aspects need to be considered:

1. THICKNESS OF THREAD. Thick thread (or more plys) = more swell. Thin thread (or fewer plys) = less swell. Although not ideal, the thickness of thread can be changed during sewing if too much or too little swell develops. 

2. HOW HARD OR SOFT THE THREAD IS. Hard thread does not flatten in the signatures = more swell. Soft thread flattens in the signatures = less swell. A compressible thread gives more control. It is often advisable to untwist hard modern threads a bit to make them softer by running them through your fingernail and thumb, and let them relax.  Waxing thread also makes it harder, so I generally avoid it if possible. Sometimes excessive kinking and twisting comes from using too small of a needle. Softer thread can fray more during sewing, though. 

3. THICKNESS OF THE TEXT PAPER. Thick paper absorbs more thread = less swell. Thin paper absorbs less thread = more swell.

4. HOW HARD OF SOFT THE PAPER IS. Soft paper absorbs more of the thread = less swell. Hard paper absorbs less thread = more swell. It is easier to control swell with softer paper. Guarding the spine will increase swell. Washing and resizing can also affect how much swell develops. Swell can also be adjusted before sewing by beating or otherwise compressing the sections.

5. HOW MANY LEAVES ARE IN EACH SIGNATURE. More leaves can absorb more thread = less swell. Fewer leaves = more swell.

6. HOW MANY SIGNATURES THERE ARE. More signatures = more swell. Fewer signatures = less swell. Some binders like to visualize this by wrapping the thread around a pencil the same number of times as there are signatures.

7. SEWING STYLE. All-along, two-on, three-on, etc. All-along produces the most swell, more “-on” sewing styles = less swell. Packed sewing produces more swell due to a small overlap of thread. This can be controlled, to produce naturally packed sewing, which has one length of thread on the cords for each signature.

8. SEWING SUPPORTS. Tapes, cords, thongs. Tapes produce the least swell, cords and thongs slightly more since the thread can overlap slightly inside the signature. Supports also differ in the amount of adjustment that can be done after sewing, ie. how much the thread can move on the supports during consolidation and backing. A professional sewing frame, such as the Nokey makes this easier.

9. HOW MUCH CONSOLIDATION IS PERFORMED DURING SEWING. More consolidation during sewing= less swell. I have often observed students sewing identical text blocks, with identical thread, end up with significantly different results. A loaded stick, or knocking down stick can help with compression, although some people prefer to use a bone folder or wedge shaped piece of wood.

10. TIGHTNESS OF SEWING. Tighter sewing makes a thinner book before pressing. Looser sewing can develop due to improper tensioning or too large of a needle. A book sewn too tightly can develop a “banana” shape, thinner at the kettle stitch. Even tension is crucial.

Best practice: sew with the thickest thread possible.

News from 1886: Hand Bookbinding is Slowly Disappearing

“Bookbinding on a small scale seems to be one of those minor industries which are slowly disappearing. Yet we think that there is always a certain need of a good bookbinder in every country town. We recollect how such a person was once maintained in a small European city by official work, and now and then a few orders from the country gentlemen. Shopkeepers and farmers as a general rule are not bibliophilists. When, however, we come in this country to look upon a book as something of intrinsic value, we will insist on real books, in proper shape and goodly binding, and then the bookbinder’s day will have come.”

The Bookmaker: A Journal of Technical Art and Information, January 1886, p. 16.


The Mother of all Insect Galleries

“M. Pignut mentions an instance where, in a public library but little frequented, twenty-seven folio volumes were perforated in a straight line by the same insect [a bookworm], in such a manner that, on passing a cord through the perfectly round hole made by it, these twenty-seven volumes could be raised at once.”

-John Andrews Arnet [John Hannett] Bibliopegia, or, the Art of Bookbinding, in all its Branches (London: Richard Groombridge, 1835), 201.

Hot Violet OptiSIGHT Magnifier


One of the few benefits of aging eyes is that you get to wear fancy headset magnifiers while working, like Donegan’s OptiSIGHT in violet!

Tool Demonstration, Roundtable Discussion, and Pot-luck Meal. CBBAG Bindery, Toronto.

Monday, October 26, 2015  6-8pm.

CBBAG Bindery, Suite 207, 80 Ward St., Toronto

This is a free event open to the public, but you must RSVP:  cabbage.gta AT gmail DOT com


I will demonstrate the making of a delrin folder using simple hand tools: a hacksaw, a file, a scraper, and micron-graded sanding sponges.  Attendees should bring their favorite tool and be prepared to discuss it. Also bring a tool that doesn’t work or you would like to alter, we can brain storm options as a group. The evening will conclude with a pot luck meal, I’ve already heard rumors of chili. Yum!


Upcoming Lecture: October 21, University of Toronto, CA


Detail from a current conservation treatment of an Aurora Store Display Monster Scene, 1971. Collection Simone Peterson. How does this toy relate to books? Come and find out!

Pulled to Pieces: Life as an Independent Book Conservator

October 21, 2015. 4:15 pm.

Faculty of Information, ischool, 140 St. George St., Rm 728

University of Toronto, Canada.

In this fast paced illustrated lecture, Jeff Peachey will discuss the variety of book related activities he is engaged in as a New York City based independent book conservator. This includes pretending to be an actor playing a bookbinder in a Samsung Galaxy Note TV advertisement, inventing the Peachey Board Slotting Machine, manufacturing leather paring knives and other hand-tools for the bookbinders, teaching, blogging, conducting research, and providing book conservation treatments for individuals and institutions.

Peachey is Professional Associate in the American Institute for Conservation, has served as Chair of the Conservators In Private Practice, was recently awarded a fellowship at the Rockefeller Foundation Bellagio Center (Italy) and is currently the Patricia Fleming Visiting Fellow in Bibliography and Book History at the University of Toronto. His most recent publication is “Beating, Rolling and Pressing: The Compression of Signatures in Bookbinding Prior to Sewing” in Suave Mechanicals: Essays in the History of Bookbinding, The Legacy Press, 2013. Currently he is researching the progressive mechanization of book structures in the early nineteenth century.

Thinking About Making: You, Artifact and Tool


A work-in-progress diagram of the interactions that take place when performing a craft.

I’ve been thinking about using tools for a while now, starting in 2004 with a preliminary (and upon rereading inadequate) exploration in Vol. 1, No. 1 of The Bonefolder. Since then, the cultural literacy of tool use continues to decline. In fact, I often encounter people who think they can pick up any tool and it will work fine without any evaluation, prepping, sharpening, maintenance, etc.  If nothing else, thinking a bit more about tools before using them can lead to more successful craft outcomes.

This work-in-progress diagram summarizes some of my thinking. David Pye’s concepts of “workmanship of certainty” and “workmanship of risk” fit nicely into it; technique forms a continuum between you and the tool, not residing completely in one or the other. In paring leather, for example, using a schar-fix or Brockman paring machine involves relatively little technique from you, but resides mostly in the machine. Of course, you still have to know when to use it, and set it up and maintain it. Failure is often catastrophic, it usually works well or it doesn’t. This is the nature of the machine.

A middle ground between you and the tool might be the spokeshave.  Although a 151 spokeshave needs to be modified to work well, it is safer and quicker than using a French or Swiss knife to scrape the leather. It requires more skill to use than a paring machine, but accidents are usually small tears, or sometimes chatter, rarely catastrophic, can lead to uncomfortably small small pieces of leather.

The most risky way to pare leather overall is with a French or Swiss knife.  The locus of technique is almost entirely dependent on your skill.  It takes a steady hand and a lot of practice, but I have seen binders become suprisingly adept at it. Similar to the paring machine, failure can be catastrophic, like cutting a hole in the middle of the spine. All three of these methods of paring are not mutually exclusive, often they are all used by the same binder for various purposes at various times.

There is also room for conservation work in this diagram. Your intention on the artifact is much more limited due to ethical considerations about preserving existing information inherent in the artifact, there often has to be more creative thought put into material selection and tool use. If you are paring the leather on the original spine of a book that will be rebacked, there is little or no margin of error. A loss becomes a loss of information in the artifact. You can’t buy another one. Your tools have to work perfectly.

Materials also place limits on an original design. Often beginners want to experiment with something new, unique or unusual.  There is nothing wrong with this, but it is usually much more difficult than performing a craft activity in a more traditional manner. Unusual materials can require unusual tools.

One of the joys of craft is when the three elements in this diagram are so integrated that we think through the tool and into the artifact. It becomes embodied, a natural extension of our hands.  We often call this muscle memory, or getting a feel for something. Again to use a paring example, when you are competent, the leather pares down quite simply and easily without much conscious thought. When you first learn to pare leather, you need to conscious of how hard, soft, stretchy and thick the leather is, how sharp your knife is, the blade angle of the knife, the bevel angle of the knife, the angle you hold the knife at, where you start the cut, and the amount of leather you are cutting at one time.  This is a lot to keep track of.

I think many of us forget how much of an interplay there is between these three elements. It is important to remember that when things are not going right in any craft, it is not completely your fault, or the tool, or what you are making: it is usually an inter-relationship that can take some time to sort out. That’s one reason why we take classes to learn things.

To be continued….