Wood—See that the back of your stave is absolutely flat. Sand it well with coarse sandpaper. See that your backing piece is absolutely flat also, and well sanded with coarse abrasive too. Apply glue (Casein, Weldwood or any resin glue) liberally to both backing and bow back. Cut a pressure board of pine or other wood ¼" thick and ¼" narrower than your wood back. Place this over the back and bind your pressure board, wood back and bowstave together with rubber strips cut from an inner tube. Cut the strips ½" wide and use plenty. See that glue squeezes out all along the joint. Let it dry for at least a day before working on your backed stave.
Rawhide—Scrape or plane the back of your stave smooth and sandpaper it with coarse sandpaper. Clarified calfskin or rawhide comes in various widths. Two pieces are used on a bow. Each length covers half the back. Soak the two strips in cold water for ten minutes and wipe off the excess moisture. The strips will now be soft and pliable. When you take the calfskin out of the water stretch it very carefully. It will have a tendency to curl-apply the concave side to the bow back. Apply smooth, thick, creamy waterproof glue along the back of your stave. At the center tack one piece to the back, run the rawhide up to the end, smooth out all air bubbles and tack it at the tip with a thumb tack. Butt your second piece against the first, tack it, and run it down the second half of the back of the stave. Be sure all air bubbles are worked out and the rawhide adheres everywhere. Watch it for half an hour or so and keep working it down where needed.
Fibre—Fibre comes in strips and is glued directly to the back with waterproof glue. It is best to cut a thin slat (¼" thick) exactly the width of your bow back, for a pressure board. Lay the fibre in the glue on the back, press the slat on, and bind down with rubber strips ½" wide cut from an inner tube. Let it dry overnight and remove the slat.
Sinew—Secure three to four dozen Achilles heel tendon sinews. These will run from 6" to 12" long. Shred them fine by pulling apart with flat jawed pliers. Rough the smoothed back of your bowstave with very coarse sandpaper. Apply Special Formula Glue (a glue developed by the writer for glueing sinew to sinew, sinew to wood, horn to horn and horn to wood) liberally along half the back. Take a handful of shredded sinew, work it in lukewarm water for a few minutes, squeeze out all water, and pull out a soft strand. Lay it lengthwise in the glue, and continue this process until you have covered the back with the strands of sinew. Lap them, and so arrange them that the back is covered. Then do the same to the other limb. Apply another layer and continue this process until you have 1/8" to ¼" of sinew and glue on the back. Apply glue between each layer. Let it dry for at least two weeks, and you will have a hard, hornlike back. The longer this back dries, the harder it gets and the more cast it develops.
Fibre Glass—Fibre Glass comes in the form of strips 1½" wide by 1/16" to 3/32" thick and about 5'6" long. It isglued to the flat back with a resin glue. Some fibre glass backs come already glued to a very thin strip of wood, and the thin wood piece (plus fibre glass) is glued to the bow back. A pressure board should be used—as described under Wood Backs. To get a good glue joint with fibre glass is quite a job.
To improve the cast of the finished bow, backs are glued to the stave while it is held in a reflexed position. Make a wooden form 2" thick, 2" longer than the stave you are working with and 6" wide. One edge of this wooden form piece is worked into an arc, the cord of which is 3" to 4". By bending around this form, your stave will come out with a concave back. The backing goes on the form first, stave on top. Start at the center, and with rubber strips (spaced 1" apart) cut from an inner tube, tightly bind down one limb. Bind all around the form. Then bind down the other limb. Before binding to the form, the stave should be tapered on the flat belly side. Begin 20" down from the ends and taper to 3/8" at the ends. This will make bending around the form a lot easier.