It’s knot what you know, it’s shoe you know…here’s the long and the short on shoelaces


Shoelaces, shoestrings, bootlaces—whatever you call them—have been around for a very long time. Shoelaces have been found in shoes that are more than 5,000 years old, which is amazing considering they were traditionally made from natural and biodegradable materials such as leather, cotton and hemp.

Shoelaces are also a very simple device; no more than a piece of string or cord, and as such, one would think humans have reached the limits of their shoelace endeavours after more than 50 centuries, and you would be wrong.

Shoelaces, or at least laces in general, are classified in the International Patent Classification (and the Cooperative Patent Classification) in A43C9. There is nothing too detailed about this class, and the only thing of note is that the rigid ends of shoelaces, or “aglets”, can be classified in A43C9/04.

There are other classes such as B21D53/58 and B21F45/14 for manufacturing aglets of various materials, and A43D98 for machines for making laces, but these will be ignored for the purposes of this article.

Let’s start with filing trends in A43C9. We have removed anything classified in A43B, which is more to do with footwear with laces, rather than the laces themselves. We have also removed any patent families comprising a single Chinese utility patent in an effort to concentrate on innovations that would satisfy an inventive step threshold.

The following chart provides the last 20 years of filings in this class. Given shoelaces are a centuries old technology, it is therefore surprising to see a rising number of applications in this field. Years 2021 and 2022 are incomplete in terms of applications yet to be published, so for convenience they can be ignored for now, but there is clearly a trend towards more applications being filed with A43C9 as a classification.

There isn’t much to a shoelace, so what sort of subject matter is driving this growth? It looks like most of the innovation is around what materials are used to make the shoelace, and what the shoelace looks like in cross section, as well as the more functional aspect of trying to stop the phenomena of them undoing themselves. It also seems that researchers are directing their efforts into the shoelace’s fellow traveller, i.e., the eyelet or hole through which the shoelace must pass.

What are they trying to make shoelaces out of these days?

In the distant past, it used to be leather or cotton, and still is. For example, JP3173003 describes the use of a denim strip, which is fashionably unravelled to form a fringe along the length of the shoelace.

Technology has, however, moved on to more modern materials, such as zippers (see US20140007457), and Velcro and magnets (see US20180116343).

On a more serious note, there are many patent applications concerned with the use of materials such as silica gels or soft outer layers to provide grip, for assisting both young and old hands, and to prevent untying (see US10314366, CN212545871 and CN209610040), and polymer fibres, wire cores, and braiding to add strength and elasticity to a shoelace (see US20110195268, CN212771270 and TWM558548).

If we move from the simple function of shoelaces, and look at what else one might want from a shoelace, we find a variety of solutions in patent literature. For example teaching aids are provided to teach children how to tie shoelaces (see US2020184848 and US2020286401, which describe a lace with markings showing where to tie a knot and where to form the loops).

Do you recall that time when you bought the wrong shoelaces, and they were either too short or too long? There are solutions for that too. CN207023426, which describes a shoelace coiled with a spring where one can pull out enough shoelace to tie your shoes, as does CN201898950. Conversely, CN201640692 goes in the other direction and allows you to produce an aglet on demand at the required length and remove the excess shoelace with scissors.

What about when shoelaces untie themselves? There are several patent applications with laces shaped to prevent this phenomenon from occurring by locking the lace together where it meets. The following are a few images taken from KR20110091967, CN110101160 and FR3040592, which show various kinds of protrusions along the length of the laces, which assist with locking.

Interestingly, there are deodorant infused shoelaces such as in CN209528051 and CN211211672, whose purpose requires no further explanation.

There are also laces that are luminescent or that have LEDs (or similar) such as CN209528051 again, and CN103099388, presumably for safety purposes (such as not being run over in the case of the latter).

There are also laces which have the added utility of a writing instrument. For example, CN203058551 discloses a shoelace where a pen forms part of the aglet.

Finally, as noted by Charles Bukowski:

It’s not the large things that send a man to the madhouse… no, it’s the continuing series of small tragedies… not the death of his love but the shoelace that snaps with no time left.

In other words, while a shoelace untying is a minor and temporary inconvenience, a shoelace breaking is on another level, and it may be assumed a significant amount of research has gone into developing an unbreakable shoelace over the years. This may well be the case, especially due to the improved mechanical properties of modern polymers, but it’s rarely been stated as the purpose. Indeed, we can find only two applications where an unbreakable lace is the primary objective, and they are FR1064307 from 1952 and CN104305644 from 2013.

Perhaps claiming an unbreakable lace is a step too far for an attorney drafting a patent specification, and that has contributed to the lack of art in this area, or is it because we have yet to truly attain that nirvana? It’s only been 50 centuries so far; surely, we can wait for 50 more. We’ll keep you posted.

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