I have been messing around with dying my own materials, using A.K. Best's excellent book as a guide. While I have had very good results with lots of materials (hackles, feather quils, marabou, rubber legs, furry foam, etc.) I am having trouble with mallard flank.

On mallard flank the colors come out very pale. I would like to get something much more intense.

I am dying small batches in just 1 cup of water, heated in the microwave and then set on a small hot plate. I typically use about 1/2 tsp - 1 tsp of liquid RIT dye per cup of water, with 1 tsp of vinegar per cup. The mallard feathers have been degreased with ivory dish soap. While most hackles will take a good color in an hour or so the mallard doesn't take much color even when left overnight.

I see lots of dyed mallard in the shops with deep color intensity, so I know it must be possible...

Any suggestions would be appreciated, Ken