Keratin is the substance from which horn and tortoiseshell are made, and is commonly considered to be ‘the same as our fingernails’. It is in fact very prevalent in the animal world, and many different forms have been used in the decorative arts. But what is it, how is it used in the decorative arts, and where does it occur?
There are several types of keratin. All are fibrous proteins, which are strong and insoluble. They are found in amphibians and reptiles as well as birds and mammals, the type found varying with the animal in which it is found. In humans keratin makes up a large part of our structure, being present in hair and skin as well as nails.
Keratin is highly tensile. In some forms it is thermoplastic, that is to say that its shape can be altered under heat and pressure, that it retains the new shape when cooled, and that the process can be repeated. This has made it possible, for example, to firstly flatten hollow ox horn, and then in a second process mould it into items such as spoons or buttons. (See ‘A Background to Horn’) Further, when heated in a damp atmosphere, many keratinous materials become sticky, which is the reason that thin sheets (for example, of tortoiseshell), can be welded together to form thicker sheets for carving, or the flat material can be made into round items such as napkin rings. (See 'A Background to Tortoiseshell’)
Looking though any ethnological collection in a museum, one cannot help but be struck by the fact that horn, hair and claws feature frequently. They have been used world wide in hunting hats, trophy jewellery or simply utilitarian items. From the magnificent collections of cats’ or bears’ claws worn around the necks of tribal chiefs as a sign of rank and power, to the humble spoon or scoop fashioned from horn by the Inuit, various forms of keratin have been used by, or adorned people for hundreds of years. The materials were easily available, and easily worked.
There are many more cases of keratinous materials being used by humans for adornment of some kind, than those mentioned here. Most of the following are not obscure, but one often forgets that these items are also made of keratin.
Horn has always been the most widely used of the keratinous gem materials, but hoof and baleen are very similar and have often been worked in the same way, indeed, when worked, it can be very hard to distinguish them from horn.
Hoof, although once widely used (especially boiled down to make glue) is not much used today as synthetic glues have taken the place of organic ones, and it is not economically viable to work the material in other ways, particularly as it is governed by strict health and safety laws.
Baleen is the name given to the horny plates that grow in the upper jaws of whales of the order Mysticeti (those without teeth), which eat plankton and similar minute animals, filtering these out by taking huge mouthfuls of water and then expelling it through the baleen ‘curtains’ which act as a sieve. Baleen has also been interchangeable with horn in the horn industry, and although it has a slightly different structure (tubes of keratin sandwiched between flat lamellar surfaces, while horn is lamellar and lacks the tubes), when once it has been worked it is virtually impossible to tell which material -- horn or baleen – was originally used.
Baleen was been used as a base for scrimshaw by sailors on whaling ships, along with ivory and bone. Nowadays baleen is no longer available as it derives from whales, all of which are protected species.
Hair from various species has been put to use for ceremonial and military regalia and attire, furnishings, and as jewellery. The hairs from the tip of an elephants tail has long been made into jewellery in Africa, either set in gold or woven on its own into bangles and other items. It is very course and can be up to 3mm in diameter. Although as yet unconfirmed, there are reports that other animal hair is now being used from unprotected species, e.g. camel. Elephant hair is covered by the same bans as elephant ivory, as the bans cover all parts of the animal.
Human hair was much used in sentimental jewellery in England and America. The practice was at its height in the nineteenth century, but started two hundred years earlier. It was used both as a love token or as mourning jewellery. Weaving or plaiting the hair was a skill taken up by many young ladies. Whole bracelets, ear-clips of even necklaces were produced in this way, often with no solid base to support the hair. When a desired shape or form had been produced by weaving or plaiting the hair over a mould, the article was boiled – thus heating it and utilising its thermoplasticity – to retain the shape when the mould was removed. More frequently hair was added to brooches or lockets, where it was often woven into a pattern.
Horsehair was used for ceremonial purposes, but also for soft furnishings, notably covering the seats of chairs. It was hard-wearing but hated by children wearing short trousers or dresses because it was notoriously prickly to sit on.
Fur, bristles, whiskers and quills all grow from the skin of animals, and are all made largely of keratin. Large whiskers and porcupine quills have been popular additions to many tribal garments, and today porcupine quills can be found in modern jewellery. The Native Americans are known to have used the quills for centuries, as a form of embroidery on items such as moccasins or knife sheaths. Porcupine quills are also found as decoration on boxes. On the porcupine, quills are a form of defence. They have backwards facing barbs that catch on the skin of an attacker, making them difficult to extract.
Feathers have been used as adornment for millennia, and are worn even today on hats and clothes or as jewellery. They are often present in the caps or helmets of some military uniforms. Feathers used as headdress have been common in all parts of the world. In some cultures they alluded to the power (for example, the suggestion of the ability to fly) of the wearer, in others they denoted rank, or even royalty. Often used in combination with other materials, feathers were the finishing touch – as with hats today.
In the mid- to late nineteenth century it was not just the feathers of a bird that were used to adorn ladies’ hats, but parts of, or indeed the whole bird. Birds’ heads mounted in gold were also used in jewellery such as ear-rings. Fortunately the fashion was short-lived.
Some birds have been almost exterminated by humankind’s wish to adorn themselves with the plumage. One such example is the kingfisher, a beautiful small bird that lives near water and is seldom seen – apart perhaps from a flash of bright colour as it swoops past.
The work using their feathers is possibly the most delicate of all feather work. The turquoise-blue feathers have been widely used in some parts of China as inlay in jewellery, especially in bridal head-dresses. It is a custom that has lasted a thousand years. The feathers are cut and inlaid in metal (usually silver), with a result which resembles enamel. Close inspection shows the presence of tiny ridges, which can be identified as the barbs of feathers.
Butterfly and moth wings consist largely of keratin. The colours of the wings are caused by a combination of pigments and optical effects. The ‘powdery’ effect of the wings when touched is due to minute scales being detached. The wings are very fragile and tear easily.
These wings can be made into colourful jewellery and other adornment, and – sadly -- they are readily available for purchase online, or can be caught in any garden.
Animals' claws were usually left intact and their shape unaltered. They were a symbol of power, worn by chieftains and hunters of stature. The Indian (Native American) tribes wore necklaces of bear claws, while in Africa or Asia the trophy would be big cat claws. The cat claws have also been set in precious metal with gemstones, and made into jewellery for the European market. The ultimate trophy was of course to have the whole foot attached to the claws, but this was used more by shamans than by ladies of fashion. Today it is illegal to trade animal claw jewellery in many countries.
Bird beaks and bills, especially those with ‘casques’ (growths above the top bill), have been used as a substitute for ivory. One such example is the helmeted hornbill, Rhinoplax vigil, which has a yellow casque with a red outer surface, apparently caused by the bird preening its feathers and rubbing oil onto the casque. Part of the casque is of a honeycomb structure, but the remaining part has been used for carvings, beads, and so forth. It is known as ‘hornbill ivory’, and the birds are today a protected species.
Pangolins and armadillos are two unrelated animal species, but both are covered in small scales. The scales provide armour for the animal in the shape of a tough, outer coat, and the scales have very sharp outer edges. As the scales overlap they allow for flexibility. They have been sewn onto garments (for example, by the Dayak people of Borneo) as body armour. Today the pangolin is possibly the most poached and most endangered of all animals.
Reptile skins (e.g. snake, alligator, crocodile), contain a large amount of keratin in their scales. They are occasionally used in the decorative arts, and to a lesser degree in jewellery. The most common uses for these skins are, of course, as shoes and bags. Many of the creatures are protected by conservation laws and trade bans.
Other forms of keratin
In most of the above the main constituent of the material is keratin, but proteins closely related to keratin are also present in some other gem materials, such as shells and pearls, where it helps to hold the (basically mineral) crystals together, in much the same way as cement holds the bricks in a wall in place. (See 'A Background to Pearls' and 'A Background to Shell')
Box made from hoof. Polished, and with a lid added.
Woven hair bracelet (left), and plaited hair in jet mourning brooch (right).
Kingfisher feather pin (left), and kingfisher (right).
Big cat claw brooch.
Carved helmeted hornbill casque (left), and kea beaks brooch (right).
Tribal helmet covered with pangolin scales.