A horn bow or horn composite bow is made from several materials, horn, wood, sinew, glued together with animal glue. These materials need considerable work before they can be put together to form a horn composite bow.
In this part I will tell something about the materials needed, and show some of the steps needed for constructing a horn composite bow.
Wood is the core of the bow. On many bows the core was made up from several pieces of wood, sometimes up to seven parts. The joints were either made by V-splices or scarf joints. Typically, on early archaeological bow findings there have not been found V-splice joints, making this a more modern invention of the late medieval times.
Horn is made from keratin and has a quality of being very good in compression. This makes it excellent material for the belly side of a bow. As to when the first horn was used in this way is a point of discussion. The oldest intact horn composite bow was found in the grave of King Tut in Egypt, but most likely the origins of the horn composite bow are much earlier. Although the horn from water buffalo is widely used, horn from sheep and sometimes cow are also suitable.
To make horn suitable for a bow, first it has to be cut out of a horn. Normally the outer side of the horn is used. If the cut out horn strip has to much twist or bend, this can be corrected by placing it in hot water, up to boiling temperature, for a short amount of time. This makes the horn more flexible, and usually after correcting the twist or unwanted bend, the horn remains in this position after it has cooled down. When a sufficiently straight horn strip has been cut out, it can be sanded down until it is smooth on the surface that is to be glued, and on this surface one can make grooves or scratches. The ‘matching grooves’ technique is in my opinion a modern technique and was not used in ancient bows. It is sufficient to roughen up the surface.
The attaching of the horn strips to the wooden core can be done with an old but very efficient technique, using rope and a wooden tool/lever. The clamping force using this method is very high, but the wood and the horn have to be rounded, otherwise the forces will not be distributed evenly.
The glue that was used for horn composite bows was collagen based. In many cases the glue that was used was made from animal skin, sinew scraps, or the swim bladder of fish. A disadvantage of these types of glues is their water solubility, and sensitivity to moisture.
When working with collagen based glues it is important to make sure that the glue is used above its gelling point.
Sinew are the shredded fibers of animal tendon. It is probably one of the oldest materials to be used as binding material. It possesses very good tensile strength, and is therefore excellent to be used on the back side of the bow. It is made from collagen fibers, and can also be used to make glue from.
The tendons are pounded with a hammer to separate the fibers, so they can be further processed by hand. The finer the fibers are taken apart, the better, because adhesion with the glue will be better. Optionally, the fibers are combed to straighten them out even more.
to be continued…