The back of the bow should be the side which is closest to the outside of the tree or
branch if it can be determined (i.e. sapwood - particularly for Yew).
In many bows, the back is sometimes made in the sapwood of the timber, with the bulk of
the bow in the heavy heartwood. Whether to use the sapwood or not is dependent mainly
on the type of timber being used. Yew's sapwood has properties that make it ideal to be
left on as the back of the bow. With many species, all of the sapwood is removed and the
back of the bow becomes the first layer of hardwood found (See below for a fuller
discussion on whitewood bows). If the sapwood is being left on to form the back of the
bow, it should be thinned down so that it only comprises up to a maximum of about 1/3
of the thickness of the finished bow. Most of the strength of the bow comes from the
heartwood. Bows can be made totally from sapwood of many tree species, but some
slight changes need to be made in the following designs to accommodate whitewood
bows.
To prepare to work the bowstave, the back of the stave should be worked down until the
full length of the back is all within a single growth ring i.e. there are no rings or 'feathers'
showing through on the back. This means following the grain no matter what twisting
occurs in the grain and in the stave. This should be done with hand tools, rather than a
saw, as it is probably the main reason for weaknesses in a final bow. If the growth rings
are cut through anywhere on the back of the bow, it is extremely likely that this will be
the place the bow will snap at. Once the back is cleaned down to the same growth ring,
the actual bow can be marked out.
Offered by Brian.