Gray Drake: a trout fly pattern from Favorite Flies and Their Histories by Mary Orvis Marbury

Hook: #8 sproat
Thread: claret
Tag: flat silver tinsel
Rib: fine black
Body: white floss
Hackle: white or very light dun
Wings: rolled mallard flank

Head cement recipe:
Goop
Xylene (epoxy thinnner)

Instructions:
Fill a quart jar half full with Xylene
Squeeze a tube of Goop into the Xylene
Shake until the Goop is dissolved; add Xylene to desired consistency

Apply with a pin or needle dipped in the liquid

https://youtu.be/AJbvJUixaCs