Popularized by Idaho fly tier, LeRoy Hyatt, in the Dean River Lantern series, Edge Bright is a stretchy plastic material that gathers light through its broad side and magnifies it through its narrow edge. It is sold in 10" X 3" sheets that are about 1/64th inch thick. The sheet is cut into narrow strips. It is wrapped on the fly so that the rear edge of every wrap is exposed. Viewed from the rear, this butt literally glows. It gives the same effect as a fiber optic cable when viewed from an exposed end. There is little doubt that a fly tied in this manner becomes easier for fish to see when they are viewing it from the rear.
The easiest way to prepare Edge Bright is to lay the sheet on a clean pane of glass. Smooth it out and it will tend to stick to the glass. Use a metal straight-edge and slice with a fresh razor blade. Width of strips vary with the size of the fly and the whim of the tier. Most common sizes are about 1/8" to 3/16". Narrower strips will take more wraps to cover a distance on the hook shank, so they build a larger diameter, steeper tapered body. If you stretch the material as you wrap it, the strip will become thinner. This may be undesirable as the thicker strips transmit more light.
The light gathering ability of Edge Bright is enhanced when it is under-wrapped with silver tinsel. Trim the end of your strip like the one just below center of the picture at left. Tie it to the hook as you see it in the picture. The end of the strip is narrowed to just slightly larger than the wire in the hook it will be tied to. 8/0 Uni Thread works best. The narrow end of the strip should form the foundation under the finished Edge Bright butt or body, so its length should be adjusted accordingly. Attach #14 silver Mylar in front of this foundation and wrap smoothly all the way back and then all of the way forward. Wrap the Edge Bright over this foundation so that each wrap over laps the one under it with the rear edge of each wrap exposed.
Tying off Edge Bright can be tricky. However thread tends to dig into Edge Bright, and it and stays in place pretty well.