Tying the wing on this fly is the same as using right and left Goose or Duck quills. Using mallard flank for a wing a few things come into mind. One, I like to make sure I have a right and left pair that has a pretty close equal curvature. Second, If the feather is slightly wrinkled I will iron it out with a steam iron on the lowest setting. third, I always try to flatten the pair by slowly pressing/indenting the quill with a finger nail or small pair of scissors by starting at the bottom of the quill and slowly working your way up to the top. Lastly after a slip from the left and right is cut out you have to be gentle putting the two together, do not rush this step or you will ruin one slip or the other. Again like Goose or Duck Quill wings make sure both left and right slips come out of the same area on the opposing flank feathers. Now using the rolled/folded technique I use more with Wood duck due to being harder to obtain and on certain scottish winged wet flies because this is the way the fly was truly tied. Lastly mallard flank makes beautiful wings but does require a little more practice and patience. Hope this helps.

Andy B