Great Dun: a trout fly pattern from Favorite Flies and Their Histories (1892) by Mary Orvis Marbury

Hook: #10 sproat
Thread: claret
Tag: flat gold tinsel
Tail: light dun hackle barbs
Body: brown dubbing - traditionally bear
Hackle: black soft rooster
Wings: gray mallard quill slips

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