What would you suggest using if I wanted to put some barring on these?
I use permanent marker pens.
Get a thin bit of cardboard and cut out thin triangular bits and use these as a template. Just brush the fly out, lay the template over the top and dab with the pen.
Once finished, stroke the top of the fly with the pen to get a darker back.
Another way, which worked really well for some "Parr" flies I tied was to use brown and yellow EP or SF and lay it along the side, starting with brown, then shorter yellow, shorter brown etc and you get nice "thumb prints" along the fly. First tie the basic shape and colour of the fly as normal, but dress a little on the light side. Then lay the colours down the flanks. You need to tie it very flat and trim straight then taper with tapering scissors. Hard to explain but I will see if I have some photos.
