The Delrin Folder

Mr. McGuire: I just want to say one word to you. Just one word.

Benjamin: Yes, sir.

Mr. McGuire: Are you listening?

Benjamin: Yes, I am.

Mr. McGuire: Plastics.

Benjamin: Exactly how do you mean?

-The Graduate (1967)

 

Bookbinders have used a variety of materials for folders. Wood, bone, and ivory are common traditional materials. The Excelsior metal folder, made from aluminum bronze, is an oddball patent from 1889. Nylon, bakelite, carbon fiber, Teflon and sometimes even steel have been used more recently.   Today, most bookbinders and book conservators use bone and Teflon. Each material has its advantages.

Earlier this summer, senior rare book conservator at Harvard Library, Alan Puglia, showed me a small spatula for pigment consolidation, which he made out of Delrin. Delrin is a plastic which was invented by Du Pont in 1960. Alan mentioned several advantages of this material, including its low coefficient of friction and rigidity. The material seemed ideal not only for spatulas, but folders.

After making a folder and test driving it for a while, I became a devotee. It is a great material for a folder ( apologies Jim Croft ) combining advantages of both bone and teflon, while not feeling plasticky and soft like Teflon. It can be shaped with hand tools. It is food compliant and impact resistant.  It is used for the stock of the M16 rifle. Du Pont’s informational Delrin booklet.

Delrin is much stiffer than Teflon, and twice as hard, yet has about the same coefficient of friction.  The hardness of Delrin is 120 on the Rockwell R scale, Teflon is 58.  Delrin has a dynamic coefficient of friction of .35, and Teflon about  .2.  More technical specifications of Delrin and Teflon. I had a lot of trouble finding technical specifications on dried bone, possibly because they can vary so much, but this article, “The Mechanical Properties of Bone” , is somewhat useful.  There is a dust hazard in working Delrin, MSDS here. Because of its slipperiness, all adhesives I’ve tried are easily wiped off, even if dried. Delrin is not quite as dense as Teflon. Teflon is 2.2 grams per cubic centimeter, Delrin 1.41 grams per cubic centimeter. Searching for “Bone Density” leads to entirely different results.

Plastics, unlike natural bone, can be made in almost any shape or size. This gives the maker a wide range of possibilities in designing a folder, since there are essentially no limitations on the shape.  I decided on this shape began by examining how I use folders and the various ways I hold them. I notice I often used a Teflon folder flat, as a burnisher, so needed it to be fairly thick and have smoothly rounded corners. Unlike Teflon, Delrin is that a folder can have large gently rounded, non-marring areas and fairly thin, knife like sharp areas that don’t distort like Teflon.

I am a firm believer in the importance of learning how to make and modify your own tools. Next week I will share some DIY tips for making Delrin folders. I’m almost embarrassed how much I enjoy working it by using hand tools. It has no grain, so can be attacked from any angle, and it is very clean, so tools stay sharp a very long time. Like most plastics, it doesn’t have a “mind” of its own but is consistently compliant with the tools and wishes of the maker. Benjamin?

 

 *****

 

DELRIN FOLDER

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This folder is carefully designed to accomplish all the general uses a bookbinder or conservator has: scoring, folding, turning-in, applying non-marring local pressure, large scale smoothing. The small rounded tip area is shipped slightly blunt, but it can be sharpened if you prefer. Delrin is hard and stiff like bone, but has a coefficient of friction similar to Teflon. It can hold a much thinner and sharper edge than Teflon. It has a nice, non-plasticy feel. I saw, file, scrape and polish these from a solid block of Delrin.

Delrin Folder:  6.5 x 1 x .375 inch. $65.00

The Ely Edge Knife

A smooth, well-cut edge is a functional and design aspect crucial to many styles of bookbinding. Historically it has served to differentiate between a what are often considered permanent and temporary binding styles. A cut edge can be left alone or form a basis for further edge treatments: coloring, paste-decoration, guilding, and gauffering. Many bookbinders do not have a massive guillotine or a reliable plough. Artist Tim Ely has been using a round French or Swiss style knife for some time to precisely cut edges. He grew increasingly frustrated at the edge retention of commonly available knives, and found the handle interfered with this different use of the knife.

For the past year or so, we have been exchanging ideas and at this point I am pleased to announce The Ely Edge Knife is available for sale.

ely edge knife

The Ely Edge Knife. Top knife with Mahogany handle, bottom New York State Cherry.

For anyone that has taken one of Tim’s fantastic workshops, you will likely recognize the shape that he came up with.  The top mounted hardwood handle is roughly 7 inches long, 1.5 inches wide and 1 inch in thickness. It is attached by epoxy and screws to the blade, made from the same A2 steel I use for my French and Swiss knives. The size of the handle makes it easy to grip using both hands.  I find that by using your dominant hand near the cutting edge, and pushing with your other, it is possible to get a very clean cut, as shown in the image from Tim Ely below.

ely edge knife 2A perfectly cut edge, trimming off previous edge decoration. Photo by Tim Ely.

Because of the hand control on the knife, there is less of a tendency to take too big of a “bite” which can often happen with a plough. It forces you to think and feel the cutting action a bit more, rather than just run the plough back and forth. I have to admit I was a bit skeptical when Tim first told me about this method a number of years ago, and since I have a couple of well functioning ploughs didn’t try it until last year. The edges I’ve done are equal, if not better, than my ploughed edges.

ely edge knife 3

An experimental knife made with multiple blade bevel angles.

One thing I noticed is that the blade angle is not as critical as it is for paring leather.  This round blade cuts basically as well from 13-26 degrees.  In fact, I would guess a steeper angle results in even better edge retention, and many plough blades are in the 25 degree range. The knife I now sell comes with a 13 degree angle, so it can be stropped into shape for quite some time and perform well, even as the angle becomes more obtuse.

The round shape of the blade also has the advantage of providing a variety of sharp areas to use, rather than just dulling a single pointed tip. It also provides a nearly zero effective blade angle in use, which Tom Conroy discusses and illustrates in his article “The Round Plough” in The Abbey Newsletter, Vol. 13, No. 3, June 1989.  This allows the blade to perform at a lower effective blade angle than it actually is, so it is actually sharper.

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Hasluck’s carriage for a chisel from 1912.

Conroy briefly mentions two earlier uses of a freehand round knife for edge cutting in his footnotes. Paul Hasluck’s 1912 Bookbinding contains measured drawings of a wood carriage that holds a chisel or plane bade. Hasluck’s design seems needlessly complex, is more like a hand advanced plough, and quite limited in terms of the thickness of the book that can be cut. Also it is only cutting using one edge which would dull rapidly. Handheld ploughs are also related to the odd looking Dryad version I previously wrote about.

unsucessfull handle shapes

Unsuccessful handle and blade shapes. I thought these larger and heavier grips would aid holding and driving the knife, but instead they create instability. 

A few concerns, though. When using this knife, it is necessary to have a dead flat press cheek, at least the one the knife rides on. I also doubt this knife should be used for cutting in-boards, since modern binders board is so abrasive. When resharpening, it is best to treat this knife like a plough blade: concentrate your work on the bevel (since the back arrives flat and sharpened) and just clean off the burr at the end on the back, since it should be kept flat or it will want to ride up on the text block as you are using it.

ely in action

Tim using the knife. He is pushing into the text with his right hand and using his left to control and guide the knife, pulling it towards himself. Best results are achieved by slicing only  a leaf or two at a time. Photo by Rich Spelker.

I would also like thank Tim Ely for providing the specifications of this knife, and more importantly, for being my first bookbinding teacher. Without his encouragement who knows if I would have even ended up in this field. It is an honor to be able to work with a former teacher.

The Ely Edge Knife. Overall length 9-9.5 inches, 1.5 inches wide. Top mounted hardwood handle 7 inches long. The blade is A2 steel, Rc 63, 13 degree single bevel.

THE ELY EDGE KNIFE: $225.00

Some Christmas Gift Ideas for Bookbinders

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A loaded stick (aka knocking down stick) is great for firmly compressing signatures while sewing. A gentle tapping can accomplish this task much more effectively than leveraged pressure.  This stick has a comfortable waxed cherry handle and a brass head.  The head is screwed into the handle and gently rounded on the edges to avoid damaging the leaves. This tool has a wonderful balance. The head is 2 inches (5cm) long, 1 inch (2.5 cm) wide, and .75 inch (1.75 cm) thick.  It is generally used on the wide portion, though the narrow area can be used if the supports are closely spaced, or there are specific areas that need more compression. Overall length 10 inches (25 cm), and overall weight is approximately 8 ounces (230 g). This is a safe christmas gift for any bookbinder, since this is the first public announcement of my version of these, and I’ve only given one to a friend.  $125.00

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Geartie

Gearties are essentially a twist tie on steroids, and are available is a variety of lengths. The one pictured above is 32 inches long.  They consist of an unhardened (steel?) core and some type of rubber (silicone?) exterior that is waterproof.  I’ve used them for numerous purposes in and out of the studio: to hold a flashlight, support a book board, keep a frozen duck breast underwater for a quick thaw. The possibilities are endless. Gearties are on sale everywhere, and are made by Niteize. Various prices for different sizes.

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Sugru

A self setting, air hardening rubberized clay like material called sugru is great for pimping out your favorite knives as well as other (non-book) repair necessities.  I made some more comfortable finger rests for my favorite utility knife,  the Olfa Model 300. Again, it seems to be some kind of silicone, the ingredients list Methyltris (methyl-thylketoxime) silane, Gamma-Aminopropyl Triethoxysilane. Available from Sugru. Various prices for different sized packets.

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Wren Haven Sharpening Card

This .25 micron diamond sharpening card from Wren Haven Tools is perfect for keeping small blades sharp. Only $12.00.