Do You Have to Wrap the Tips of a Sinew Backed Bow

The bow of Hunza (Afghanistan) embodied the main characteristics of composites, but the horn facing consisted of several strips of ibex horn on a wood core. The sinew backing was coarse and rough with the entire bow wrapped with whole tendons. The ears show little backward angulation, and there was little or no recurve or reflex. However, such bows are still in use.

Rare old bow from Hunza (N. Afghanistan), rough sinew backing, thin strips of Ibex horn on belly, bound with whole tendons. Release method unknown. Arrows 30-31" long.

Same bow braced.

Partially drawn. 134

Replica of prehistoric Hungarian Avar horse bow, fifteenth century, by Dr. fulius Fabian. Side plates ofsiyahs of antler, blue ox horn facing.

Bow at full draw. Loops on string too short so effectiveness ofsiyahs reduced.

Horn bow. Jam. Long center section of wood with brass rings to hold limbs together. Limbs spliced about center of recurve and wrapped with strong cord.

Java horn bow, take-down type with ferrule, braced.

Same bow, full draw.

The copy of the prehistoric Hungarian Avar bow by Dr. Julius Fabian is incorrect. He did not know the proper angle for the ears, as he wrote in a personal letter, and wasn't sure how much reflex was present on the original bows found in burial sites. Not realizing that the string loops on the originals were long, perhaps eight or nine inches, the usefulness of the ears on his reproduction was never appreciated.

It should also be noted that self horn bows were made in the same areas as the composites, Arabia, Africa, India, Java, and Japan.

NORTH AMERICA

Had not Columbus, among others, led Europeans to the settlement of the Western Hemisphere instead of some explorer from Central Asia, the modern North American archer might well be using short, recurved, composite bows and a Mongolian release with a thumb ring or guard. However, until recent decades, the English type longbow was the most common bow form along with the Mediterranean or some variant of the three finger draw and release. The straight bow was here before the arrival of the Europeans, who only perpetuated the straight longbow form present on the Atlantic side of the continent south through Florida, Central America, and South America down to Tierra del Fuego.

Century-old Apache bow, 38" by 1Repaired and restored.

Southwest U. S. Apache bow ofmesquite or ironwood, central reflex, string follow. Thin sinew backing and sparse sinew wrap, 44" long, 11/4" wide at center, 5/8" thick. Over 100 years old.

The idea of the short, recurved, reflexed bow coming to North America from Asia is evident in the shape and construction of many bows throughout Western North America and in the Arctic east to Greenland. The two types may have blended in the Central Plains where our present interest is directed to the sinew-backed horn bows.

The great majority of the old composite bows south of the Canadian border were wood backed with sinew. Many varieties of wood were used, but the best were from slow growing, bushy trees or shrubs, woods of fine, sometimes almost invisible grain, tough, resistant to splitting and permanent compression.

A small proportion of the composite bows were made of sheep (Bighorn) horn, or elk antler with sinew applied directly to the back of the horn or antler strip, a simplified form of the Asiatic or Oriental three layer construction having a wood or bamboo core. However, if short pieces of horn were used, such as buffalo horn, a wood core was still necessary to avoid cumbersome reinforced splices.

Buffalo horn bow at low brace height with old Cheyenne arrow. Horn sections laminated to wood core, then sinew-backed.

Buffalo horn bow at 23" draw. Full draw is 25-27". Bow is 44" long, 5/8 " thick at center, 3/8" thick at mid-limb, 15/16" wide at center, and 5/8" wide at tips.

The composite horn or antler bow, though less common than the wood composite, was widely distributed throughout the Northern Plains and westward to Idaho and Oregon. One elk antler found in Oregon showed a long strip crudely cut out on the front side estimated to be at least twenty-four inches long. A second shorter strip was partially cut for removal on the back side of the same antler. It is important to note both strips appear straight as far as any lateral deviation is concerned.

Good strips of elk antler are not now easy to find because antlers are sold to Oriental markets for medicinal purposes, and hunters keep good sized antlers as wall trophies. Adequate strips can be cut from mediocre antlers beginning on the main beam and extending out onto a large tine. A flat bend in such a strip is not of much consequence. Two pieces of antler as short as seventeen or eighteen inches are enough for a sinew backed bow.

It would be interesting to reexamine the old elk horn bows to be sure they really were of elk rather than caribou. Caribou provides longer and straighter

Old sheephorn bow of single piece, no reflex, slight recurve, 32" long.

Relaxed elk antler bow, sinew backed, slight reflex and recurve. Made by author.

Elk antler bow braced, re-tillering needed after much use.

Recreation of rare type of composite found on the Northern Plains; buffalo ribs glued to wooden core, sinew backed, 36" long. Made by Jim Hamm.

Caribou antler bow, reflexed, recurved, heavy sinew backing. Made by author.

Bow at full draw. Needs thicker riser at center and retillering for more bend toward tips.

Pieces of antler. Woodland caribou shared the same area with elk, and a remnant of one herd still persists and migrates across the Montana-Canada border.

Original sheep horn bows probably came from the Rocky Mountain sheep since the Stone or Dali sheep ranged much farther north. The Dali horns are less massive, less apt to be broomed, and generally provide a longer strip of good horn. Jack McKey, from Alaska, prefers making bows from Dali sheep horn despite the narrow tips.

The construction of a sheep horn bow is a long process requiring much care and understanding of the materials. If Dali sheep horn is selected, the narrow tips may be left stiff to act as ears as in the Asiatic composites. Whatever horn is used, the pair must be carefully examined for soundness and absence of damage from insects. The outside strips can be cut off with a band saw and trimmed to a degree where they can be heated by boiling and gradually uncurled. The band saw cut is not an easy process. The saw blade tends to run off to one side due to the spiral of the horn; thus, a pair of horns may be inadvertently ruined. A series of contiguous holes, about half an inch in diameter, drilled into each side of the horn along the intended cut will prevent the saw blade from binding. The horns can even be split along this line with a chisel.

Only a thin strip of horn is needed for the wider middle and central part of the bow limb. About one quarter inch is usually enough. If a stronger bow is eventually desired, more sinew may be added on the back. The addition merely moves the neutral plane more toward the back of the bow, and the sinew over which it is applied acts as a thicker spacer or core. There is little or no tension or

Sheep horn, rough cut, 24" outside. Note 90 degree twist from base to tip.

Compression near the neutral plane. Most of the tension and compression are nearer the surface of the sinew and horn respectively. A good example of this principle can be seen in the early aluminum bows in which the cross section was the shape of a flattened "I" bar, the centerpart being a spacer instead of a wood core or, in this case, sinew or horn.

Two strips of horn about twenty inches long, spliced at the center, will yield a bow. Old spliced bows are about 38 to 40 inches long, though one in the author's collection was made of a single strip of sheep horn only 32 inches long backed with a thin layer of sinew, then covered with a waterproof layer of pitch.

The rough-cut horn strips are left as wide as possible so any lateral curvature can be corrected by trimming the sides rather than by heating.

When the two strips are shaped, they are spliced at the center or grip, usually by a simple lap splice which may be covered by a short piece of horn or antler as a riser. The splice is held by glue and/or pegs of horn, bone, metal or antler through all overlapping thicknesses. The riser stiffens the center of the bow and reduces the flexing in this area.

If the two horn strips are shorter than desired, a butt splice may be used, also covered by a riser. Even a short third section of horn may be interposed at the center and lap spliced to the two limbs. Now the horn base can be tillered slightly, but since it is unprotected by sinew, the horn will not tolerate much tension on the back. The neutral plane at this point is somewhere within the horn itself.

Bare horn base strip braced and tillered. Lower limb, at right, intentionally stiffer than upper.

Finished strips reflexed, recurved, ready for sinew.

After gentle tillering, score the back surface with a sharp saw blade placed crosswise and dragged along the length of the horn.

Now the sinew may be applied, but some comments are in order for a better understanding of the use of sinew, glue, horn and antler.

Collagen is an extracellular, insoluble, fibrous protein found in bone, cartilage, teeth, tendon, skin and in most mammalian tissues or organs. It is also found in tissues of other vertebrate animals such as fish. When denatured by boiling, collagen becomes gelatin, a complex protein soluble in hot water and which also swells in cold water. It is a colloid made of a system of particles having linear dimensions of molecular or microscopic character. The particles may be large molecules such as proteins, or solids or liquids which remain dispersed indefinitely and take up water to form gelatin or gel. The structure is comparable to graphite which is one arrangement of carbon atoms held together by electro-magnetic bonds in a linear arrangement.

Antler is like bone in that it contains a considerable amount of collagen and, like bone, contains about 60% calcium phosphate. When antler is heated to alter its shape, it is possible to boil out the collagen and leave little but the brittle bone mineral salts. The result is partly the cause of breakage when stresses are applied to the finished bow in use.

Conversely, a bone soaked in vinegar or acetic acid dissolves the calcium phosphate and other mineral salts leaving only the supporting collagen structures. The remaining "bone" is flexible like a piece of rubber. So, antler strips should be heated in water but not boiled repeatedly or for long periods.

On the other hand, horn is keratin, a scleroprotein found in claws, nails, feathers, hoof, horn, and outer layers of skin. Horn will not make glue but can be heated and re-heated without appreciable structural damage.

Since animal glues and sinew are so closely related chemically and structurally, they bond well when placed together under proper conditions. Animals glues bond well to wood by allowing penetration of glue into the porous surface.

Horn does not have a porous surface which allows glue to penetrate, and the chemical dissimilarity does not allow bonding. The horn surface must be roughened or grooved as clearly shown in the Turkish bows where the grooving doubles the contact surfaces and changes the force of separation from a direct pull to a shearing force.

The best glues are made from hides, the poorest from bone. A mixture of animal and fish glue was preferred by most old time bowyers. The Chinese added lead powder, probably lead sulfate, to some of their glues for added strength.

The best sinew for bow backing comes from the back leg of elk, moose, or caribou. It should be removed before the legs are cut off preparatory to quartering or butchering. Make a cut through the hide on the back side of the leg from the dew claws up the hock to expose a large flat tendon about ten inches long. This tendon and the one under it are usually referred to as the Achilles Tendon. In comparing to the human anatomy, this is not the Achilles Tendon which extends from the hock up on to the ham muscles. Removal of this will not interfere with hanging the animal on a hook or gambrel. Under this tendon is another round tendon extending from the dew claws to the hock where it passes through a tunnel on the inside of the hock and fans out on and into the ham muscles. Cut this tendon off with some muscle fibers which can be scraped off later. The tendon can then be pulled back through the tunnel. The tunnel may be opened if necessary. Now the tendon can be cut off above the dew claws. There is another small tendon parallel to this which can also be used. Several very thin loose layers of tissue sheathe the tendons. Remove these as far as possible. Tendons up to 24 inches long can be removed in this manner.

Don't forget to wash the tendons in Clorox water or a similar antiseptic and wash the hands after handling tendons or legs. These animals can carry bacteria or disease very serious, or even fatal, to humans.

Tendons can be dried or frozen and kept almost indefinitely. The dried tendons can then be pounded with a light hammer or wood mallet and teased apart with hands or pliers. The shredded tendon can be degreased, though this is usually not necessary. The Turks used a weak lye solution (ashes) which saponifies the remaining oil. However, one product of saponification is glycerine which might be left behind, though glycerine is sometimes used in glues. Oil removal may be hurried by washing with acetone, but the washing must be repeated since just one rinse of acetone evaporates, leaving the oil behind.

Backs strap sinew can also be used for bow backing, but leg sinew has more frayed fibers that hold the entire backing together better. Unless a generous supply of sinew is available, that from the back is reserved for strings, wrapping feathers and points, and for sewing quivers or other leather objects.

Some bowyers like to use hot glue for sinew backing. This requires less time but doesn't leave time to express excess glue. Liquid hide glue seems preferable, provided allowance is made for slower drying process.

First, a thin, watery layer of glue is applied to the back of the horn. Thicker glue fills the scoring and partially obviates its usefulness. A bundle of the shorter fibers is then completely soaked in glue, placed on a flat surface, held with a finger near the center, and "combed out" flat toward both ends with fibers parallel. This flat bundle is then laid on the bow, and similar bundles are laid on, overlapping about one third to one half, like shingles. The first sinew is applied at the bow tips and successive sinew layers applied toward the center of the bow. The long sinew bundles are applied last. These will usually reach from the bow tips to the center and actually overlap at the grip. With liquid hide glue, there is no reason why the complete sinew job can't be done in one session. The cold liquid hide glue does no damage to sinew.

Now the entire bow must be wrapped to squeeze out excess glue. Indians of the West Coast employed strips of bark, and one old bow I've seen from Northern California still showed marks of cord wrapping in its sinew back. The Turk bowyers used strips of linen cloth about one inch wide. The excess glue oozed through the cloth. Wrapping with strips of rubber about an inch wide (cut from an old inner tube) does a better job since compression is preserved even as the excess glue is squeezed out, and the remaining glue dries and shrinks. It is best to begin the wrapping at the grip and wrap toward the tips making each wrap abut on the preceding one. Even a second layer of wrapping might be applied over this. The excess glue will ooze between the laps. By beginning at the center and wrapping toward the tips, the sinew is squeezed out lengthwise so no waves or squiggles are introduced.

Sinewed sheephorn bow after tillering.

Braced. Note lower limb slightlp less flexed than upper.

Bow must be perfectly balanced, or it will flip-flop. This demonstrates the remarkable flexibility of this type bow.

Sheephorn bow at full draw of 20"+.

In twenty-four to forty-eight hours, carefully take off the wrapping and remove the ridges of excess glue. Reapply and remove the wrapping every day until the sinew backing is firm. The wrapping may be left off with sinew exposed for several hours each time between applications to permit faster drying. At this point, smooth out and further compact the backing by rolling with a small roller about two inches wide and an inch or so in diameter such as a paper hanger uses.

When the glue is dry enough so the bow can be handled, small strips of sinew from the back strap are removed, dampened, soaked in glue and flattened out to wrap the grip at its upper and lower ends and the tips for about two inches. Moving the ribbon of sinew from side to side while wrapping results in a flatter, smoother surface. The wrapping prevents the sinew-backing from lifting at the tips and at the recurve. Some California Indian bows and some Korean bows are completely wrapped with sinew.

The backing may extend over the sides of the horn to help prevent lifting along the edges as drying occurs. It does not help much in preventing recurrence of any lateral curve taken out in the process of shaping horn or antler. The belly has a "memory" of its original shape and will sometimes revert to it after a bow is finished and has been used for awhile.

Elk sinew (top to bottom), back strips 22 " to 24" long, leg tendons, leg tendon pounded and partially shredded, bundle of shredded leg sinew.

Northern California style sinew-backed bow braced, 40" long, 3" maximum width. By author.

Same bow at full draw showing typical arc.

Old Northern California sinew-backed yew bow completely wrapped with sinew. Strips of mink skin used as string silencers.

Once the sinew is in place, the bow can be put away to dry for two or three months, held in reflex shape with a temporary cord on the reverse side.

When ready to brace, final tillering can be done by scraping the horn or by warming while braced. If the bow is too light, more sinew may be applied, using long fibers as before.

After the sinew dries, fine, longitudinal fissures may appear in the backing. These are of no concern but may indicate that all the excess glue wasn't removed. The California Indians used a mixture of powdered clay or chalky soil (diatomaceous earth?) mixed with glue to fill in and smooth out the roughness of the backing. A mixture of inorganic (mineral) pigment and pitch was used to draw designs on the bow and at the same time served as a waterproof covering.

Incidentally, the California Indians also used a glue made of the air bladder of sturgeon dried, cut in pieces, and boiled to the consistency of cream. This dries slowly but is a good glue.

Elk antler is also an excellent base for a sinew backed bow and may have been used almost as frequently as sheep horn. The bend in the strip can be changed by heating in hot, not boiling, water.

Once the antler strips are obtained, they are treated almost like the sheep horn. Unlike the sheep horn, the central part of the antler is porous or honeycombed. This is of minor concern as long as the dense cortex or outer layer is on the front surface of the strip. This is the part that takes the brunt of compression. The spongy core acts merely as a spacer since it is in or near the neutral zone.

Caribou antler provides strips superior to elk. The cortex is thicker, more dense, and has few grooves or channels on the surface from blood vessels present under the velvet. Very long strips can be obtained with only a single arc and no secondary side curve. These come from large bulls, especially those that do not have the usual small tine on the back side of the main beam. I am convinced that some of the so-called elk horn bows might have been of caribou antler which was commonly used farther north in Arctic regions.

Other materials of short lengths can and have been used for bow facing. But these require a supporting wood core to which the short segments such as buffalo horn or rib bone are glued. The ends are butt joined and sinew applied to the back of the wood core.

Eskimo bow, 58" long, wood, single cable of sinew lashed to wood full length. Ivory struts to support cable at angles.

After a year or so of use, most horn or antler bows require adjustments or realignment due to a tendency to return to the original shape of the horn. This may require at most the complete dismantling of the bow, rejoining the limbs and replacing the sinew. Sometimes, only heating and bending the tips slightly may suffice.

In the author's experience of making horn and antler bows and restoring or repairing old ones, the sheep horn bow seems far better than antler bows. Antler bows seem to stack at full draw, but horn bows do not have such an abrupt limit. Perhaps the horn has better or greater compressibility before rupturing or crushing. Measurements on the caribou antler bow show the sinew stretches 1.8%, and the antler compresses or shortens only 1% at which point the antler at

Eskimo wood bow, Arctic type, 45" fixed permanently.

Long. Double sinew cables twisted opposite directions and

Eskimo bow, Arctic type, 29" long. Made of five pieces of musk ox horn and one tip of caribou antler. Sections are butt spliced with antler pieces overlaid and pegged on, then wrapped with sinew. Loose backing and string of braided sinew.

Bow at partial draw only. This type of bow usually used as a set bow, held at full draw and released when an animal tripped a trigger.

Eskimo bow, 40" long. Musk ox horn, "V" splice at center, caribou antler tips, lap spliced. Loose braided sinew cordage bundled on back.

The bow center begins to disrupt. These figures also point out that the neutral plane lies only about one third of the way from the front of the bow. Not enough antler for the amount of sinew! Correction can be made by allowing the tips to bend more or stiffening the center section by adding antler as a riser.

Composite bows of horn or wood and sinew north of the Canadian border and on into Arctic usually had loose sinew backing of braided cordage. The base may have been of combined sheep horn plus caribou antler, musk ox horn plus caribou antlers, caribou antler alone joined together, or even baleen. Most of these bows showed traits of the eared or angled recurve bows of the Chinese or Asiatic design. The tips did not bend or work, instead, all of the bending was done in the central part of the limb. Some bows were simply straight, with no reflex or recurve. Sinew was usually from caribou, with back sinew braided rather than twisted into cords. The cordage was applied from end to end as tightly as possible, sometimes with the bow slightly reflexed. The cords were pulled against the bow, and held by sinew wrappings. Often there were two ropes of cordage twisted in opposite directions by inserting "sinew twisters." If the cordage were twisted rather than braided, one would become looser while the other became tighter or shorter. These sinew twisters were left in place while the bow was used and removed later to allow the cords to relax. Single cables on the back may have been twisted tight and held permanently in place by a strip of rawhide inserted through the center of the cable at the grip and wrapped around the bow several times.

Some of the bows with back angled tips had struts under the cable. When the bow was braced and drawn this mechanism further tightened the cable with much the same effect as a rigid "ear" of the Chinese bow.

The baleen bows of Greenland consisted of two strips of baleen about an inch or more wide, which overlapped through most the length of the bow to the backward angle of the tips; the tips were of one thickness only. Each strip was about a quarter inch thick. Loose sinew backing was applied on the baleen base the same as on wood or horn bows and bound to the baleen with transverse wrappings. Fine strips of rawhide "babiche" from ribbon seal were sometimes used instead of sinew cord. Remnants of these baleen bows found in Greenland

Eskimo bow, Arctic type, musk ox horn, the pieces spliced by overlapping 5" splice which is riveted. In order to obtain each limb of 24" by 1 1/2", a very long pair of horns must have been used. Cordage applied on back and tied on flat.

Eskimo bow, 33" long, three pieces of caribou antler, lap spliced, copper riveted, then wrapped. Braided cord backing and string.

Morphological classification of bows, source unknown but probably Balfour, late 1800's. Below "A" the bows are of wood or horn, above "A" the bows are of wood and horn.

Are sufficient to show the construction, though no complete bow has been reported.

The composite horn bows of North America constitute only a fraction of the many more sophisticated composites of Europe, Asia, China, Russia, Korea, and Japan.

To understand the underlying reasons for details of construction of a composite bow, one must be an archer, know some engineering principles, and know a bit of chemistry. But, above all, one must replicate one or more of the old bows to really appreciate the old bowyer's ingenuity.

Do You Have to Wrap the Tips of a Sinew Backed Bow

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