About three years ago I made a D bow from a small diameter black locust tree which had been drying in rafters for years. I made the bow half sapwood, half heartwood. It is 66" long, 11/8" wide at the widest and now pulls 58# at 27", although originally it was pulling 60. I shot the bow a lot and loved it. The heartwood sapwood contrast is very pretty. It has 11/4" of string follow and seemed very fast, although there was a lot of handshock. About a year ago, I was horrified to see there was now a lateral crack on the lower limb going across the sapwood. It was just surfacy but I didn't understand how this suddenly happened after two years of consistent shooting. I then read in one of the TBB that black locust sometimes does not take well to leaving on the sapwood. I also took it out in a lot of cold and snow at one point, so maybe that affected it.
I kept shooting with the crack for a few months. It didn't get any worse. I then took some small, messy pieces of deer leg sinew (it wasn't good sinew, but it was all I had at the time) and used that and hide glue to cover the crack. I wrapped the sinew all around to the belly. There are little messy pieces sticking out. This was the first time I ever messed with sinew on a bow. The sinew dried and I've been shooting it ever since. It looks terrible though. So my question is, can I file and sand this sinew to make it look nice, or will that make it chip or peel off. I don't want to ruin a shootable bow. Here are some pics.