Ian’s Brass Ass is a super cool and extremely popular fly developed by Ian Colin James. I believe most people tie the Brass Ass larger than this but I really prefer them small, like this size 18 or even a 20.
Here, I’m going to be using a Dai-Riki #125 in size 18. Begin by getting the hook firmly secured in the jaws of your tying vise.
Brassie-sized copper-colored Ultra wire makes up the majority of the fly. A 10” length will usually make 2-3 flies. Starting right down by your vise jaws, take touching wraps with the wire, up the hook shank, toward the eye. If there are little spaces between wraps, don’t sweat it, you can close them up later. Once you’ve wrapped to just in front of the hook point, use your thumbnail to press the wraps rearward so they contact and compress against the vise jaws, as shown here. I like to use an Exacto knife to cut off the excess rear portion of the wire. Just sort of push down between the vise jaws, and the wire should break off clean. Pull the wraps forward and tuck that nasty little wire end in close to the wraps in front of it. You can then move them all rearward, a short ways down the bend, and continue taking a few more forward wraps. You do want to leave a bit of space between the very last wire wrap and the vise jaws.
For thread, black UTC 70 Denier is an excellent choice. After loading your bobbin, get the thread started on the hook shank behind the eye and take a few wraps rearward before snipping or breaking off the tag. Then, take several wraps over top of the front end of the copper wire, brace the hook with the nozzle of your bobbin and helicopter to break the wire off close. Take wraps of tying thread all the way back to the wire. You want it to end somewhere close to the hook point.
Ian used Hedron 3D orange-colored holographic tinsel for the cheeks but here I’m going to use orange-colored Sulky Holoshimmer. Once again, a 10” length is enough to make numerous flies. While holding one end of the material, take thread wraps over the tinsel to secure it to the top of the hook shank. Then fold the rest of it back and take thread wraps rearward, securing the tinsel as you go. End with your thread behind the hook eye. Pull the strands of tinsel forward so they lay on either side of the hook, and take 2 - 3 thread wraps to secure them. Check to see that the cheeks are aligned correctly. Next, fold the strands back and take a few wraps over top of them to make sure the slippery material won’t pull free. Carefully cut the excess tinsel off as close as possible. Do a 3 or 4 turn whip finish, seat the knot well and snip or cut your tying thread free.
I like to apply a small drop of UV cure resin to a sticky pad, turn the fly upside down and then use a bodkin to pick up just the tiniest amount of resin. Carefully apply the resin to the wire wraps, trying to keep the coat as thin as possible. You definitely want the resin to go over top of that final rear wire wrap but not so far that it gets on your vise jaws. When you’re happy with the look, pick up the UV torch and use it to cure the resin. You don’t have to go nuts here, just enough so the resin sets, and doesn’t sag.
Now go back to your sticky pad, and pick up another slightly larger drop of resin. Use this to build up a bulbous little thorax. Take care so the resin doesn’t flow into the hook eye. Again, when you’re happy with the look, give the resin a good shot of UV light. Applying just small amounts of resin at a time, and lightly curing between them, is the way to go. Trying to do everything in one coat will oftentimes result in a misshapen kind of mess. In the end, give the whole fly a final long shot of UV light to cure the resin and the Brass Ass is ready to fish.
Try ‘em in different sizes and colors. It really is an exceptional pattern.