After the sinew dried for a day I decided to add the rawhide backing so it could all dry together. I sanded the sinew back again to smooth it out somewhat then prepared to add the rawhide. I first hydrated the rawhide in warm water...
...then washed it well with Dawn and warm water then rinsed it well and put it back in warm water so it would stay hydrated...
...then I rolled the wet rawhide in paper towels to get the excess moisture off of it...
...then it was time to size the sinew back and the rawhide before putting them together. I did this twice over about 30 minutes to ensure good adhesion.
I only do one limb at a time and overlay the rawhide pieces at the handle. Once the rawhide is in place I wrap it with strips of old bed sheets for about an hour. The strips of old sheets allow the moisture to evaporate as the strips hold the rawhide to the back...
After an hour I I remove the cloth strips and check the rawhide for trapped air and excess glue. I work them out with my thumb. If that doesn't work I use a sharp razor to make a small slit lengthwise and push out the air and excess glue.
Once both limbs have been covered with the rawhide it's time to set the bow aside to let everything dry.
This morning I trimmed the excess rawhide from the sides and belly of the bow. And now the waiting game begins. I'll probably give the bow at least a week to dry. With the wood stove in our house and even with humidifiers running things dry our pretty quickly.