A background to bone and antler

A BACKGROUND TO BONE AND ANTLER

Bone, as a material, needs little introduction. Bones are part of an animal’s physical make-up. The bones of mammalian skeletons consist of calcium phosphate and collagen (a fibrous protein that makes up connective tissue and makes bones tough). Bone from any animal can be used in the decorative arts, but the most common is ox or cow long bones (in the legs).

Antler is a very fast growing form of bone, and contains a little more collagen than normal bone. It is not horn, although it is not uncommon for antlers to be regarded as a form of horn. This misunderstanding possibly arises from the fact that horns and antlers both grow from the top of the heads of some mammalian species, but animals bearing horns or antlers come from different taxonomic families. Bovids (for example: cattle, sheep, goats, antelope, bison, and buffalo) all have horns, which they retain and which grow throughout their lives. Cervids (deer), have antlers, which they shed annually.

Sambar deer in Thailand, and shed moose (elk) antler.

In all the various species of deer -- with the sole exceptions of reindeer and their American cousins, caribou – only the males carry antlers. Antlers vary greatly in size and shape, depending on the species of deer. Some deer have quite small antlers, while the magnificent antlers of a fully grown red deer (or elk, as they are called in the United States), are large but slim and with many branches. Other species have antlers with broad, flat areas that end in points. These are known as palmate. The largest palmate antlers are borne by moose (also known as elk in Europe).

The purpose of bones is obvious, but the purpose of antlers is less so. They are used for sparring, and for display. The more mature a male deer becomes, the more magnificent his antlers, growing larger and possibly with more points or ‘tines’ annually, depending on the species. Finally he reaches a point when the antlers do not increase in size, and soon after that he may face competition from younger, more agile, mature males.

Section of antler complete with velvet.

Whilst growing, antlers are covered in a furry skin called ‘velvet.’ This skin is supplied with nutrients from a mass of blood vessels. These dry up, causing the skin to die and fall off, before the animal sheds the bony antlers underneath. After some weeks the whole process begins again, and the animal starts to grow a new pair of antlers, complete with velvet.

CHARACTERISTICS OF THE RAW MATERIALS

Bone and antler can be carved, turned, and dyed. They are rigid materials and cannot be softened or heated to alter their shape. They have both been confused with ivory. Most bone is the same creamy white colour of ivory, though extremely old bone artefacts may discolour to grey. Much antler is also creamy white, although some is of a more beige or greyish colour. Reindeer and caribou antler is an example of this.

Cigar cutter with ridged surface of antler intact, and corkscrew

with the surface polished away.

Greenland Inuit 'Tupilak' carving

in reindeer antler.

It is most usual to find antler used (for example as knife handles) with the outer surface intact, which makes identification easy. The surface is ridged and slightly darker than the interior, which is not the case with bone or ivory. (Fossil ivory may have a dark outer surface, but it is not ridged). Only when this surface has been removed from antler can queries arise.

If a piece of antler is examined in cross-section, it will be seen that the entirecore is cancellous, i.e.it has a honeycomb structure and resembles a spongy material. It is in fact very hard and durable, but it does not take a good polish. Most bone is hollow (with cancellous areas at the ends near the joints only), and antler can only be confused with it if the central core of the material has been completely removed.

In almost all instances the presence of the honeycomb core is diagnostic of the material being antler. There are, however, a few exceptions to this. The bacula (penis bone) of some animals also has a honeycomb core, as for example the fossilised walrus bacula that can sometimes be found on the market. But while antlers have a ridged outer surface, bacula have a smooth one, and the core looks slightly different.

Left to right: antler burr; cross-section of antler showing cancellous core, and cross-section of walrus bacula.

It is possible to come across ivory that is hollow depending on which part of a tusk has been used, and from which animal the tusk originated. (See ‘A background to Ivories’.) An item made from a solid piece of material indicates that it is ivory.

Various ivories have distinguishing structural features (see ‘A background to Ivories’). Bone and antler do not have these features, but instead they have Haversian canals, which contain blood vessels and nerves. They run longitudinally. Seen in cross section Haversian canals appear as tiny dots, and seen along the length of an item they appear as irregular, fine lines. They are totally lacking in ivory.

Camel bone bracelet showing Haversian canals in cross-section (dots), and longitudinal section (lines).

Some bone has coarse Haversian canals, which are easy to see, e.g. camel bone. Other varieties may have canals that are so fine that they could almost be missed on examination. In the case of older items, there is a good chance that the small indentations and grooves may have gathered some dust or dirt over time, making them much easier to recognise.

As already stated, most bone is hollow. It can still be made into items such as boxes by joining pieces together. Indeed ivory boxes are also usually made in sections to make the most economical use of the material available. Identification becomes more complicated with small items like carved beads. The illustrations show one such bead which resembles a piece of hollowed ivory but is actually made up of three sections of bone: the central, hollow part, and a top and bottom sections. Careful inspection discloses Haversian canals.

Left to right: bone box made in sections (and showing Haversian canals); bone bead imitating ivory, and join in sections of bead.

Historically, making the best use of materials sometimes involved combining ivory and bone in the same piece. Old fashioned walking canes are an example of this, where part of the shaft may be made of sections of hollow bone, while the intricately carved handle is made of ivory.

A master carver will use the material’s characteristics for effect. Thus the illustrated carving of a woolly mammoth is made from a very large antler (moose), with the solid, outside section removed, leaving the cancellous material, which gives the impression of woolly fur. The tusks are made of bone.

Woolly mammoth carving made from the central core

of antler, with bone tusks.

The shape of a completed item may give an indication of whether bone or antler has been used. As neither material can be flattened or shaped other than by carving and joining sections together, they were often made into items that retain something of the original shape of the raw material. It must be remembered, however, that some bones are very large. An example of this is the pan bone (or lower jaw bone) of a whale, which can be huge and very flat. Pan bones have been used for scrimshaw, or, in past ages, for ecclesiastical carvings.

IMITATIONS AND TESTS

Plastics have been used to copy all organic gem materials. From the early semi-synthetic polymers such as celluloid and casein, to the modern polymers, natural materials such as tortoiseshell, coral, ivory and so forth have all been imitated.

Plastics are warm to the touch, as are bone and antler, but they are much lighter and therefore cannot be confused with the natural materials unless a filler has been added to give it weight (i.e. a powder of some sort added to the plastic in manufacture). Plastics must be formed, which usually leaves a trace of the manufacturing process, such as marks from a mould. Occasionally air bubbles may be present, which would not occur in bone or antler. The edges and corners of a plastic ‘carving’ would be less sharp than those carved by hand. Further, plastic imitations have no signs of Haversian canals, or honeycomb pattern core.

Plastic imitating antler.

The best test for bone and antler is visual examination, using a good light and turning the piece to view it from all angles, if this is possible.

Using ultra violet light (UV) to test for fluorescence is of little help as bone, antler and ivory will all fluoresce with much the same chalky blue colour. Plastics are inert under UV light, with the exception of casein – one of the early plastics which has been used to imitate ivory. It should be remembered, however, that ivory has always been valued higher than bone and antler, so it is more likely to find examples of bone, antler and plastic copying ivory, than of finding plastic imitations of antler and bone. Nonetheless, they do exist.

Bone and antler are not expensive raw materials, but they must be processed by hand. They cannot be used in the same way as plastics for mass production of inexpensive items.

TRADE BANS

Some animals are protected by trading bans and agreements, for example it is no longer possible to obtain pan bone for carving as this derives from whales, which are protected species. But bone and antler are generally in plentiful supply, with limits being imposed more by health and safety regulations than by trade bans.