most hairs and feathers are processed in a solution of formaldihyde, which keeps them from stinking. All that are dyed get a double treatment, the dye acts as a sealer. White or Natural is about the worst. Go to your nearest Janitorial supplier or carpet cleaning company and ask for a can of pet urine remover. This stuff is fantactic, it breaks up any crystalized body fluids and body oils, then simply wash with ivory soap and warm water, ivory is the only soap without alcohol and perfume, alcohol will destroy non living feathers and hairs. Good luck with your project.
Just Add Water