Hi Bron, I use feathers quite a bit in my work. The following is the process that I have been using (after compiling a great deal of research on how to properly sanitize and prepare feathers). Step 1: Freeze them for 24-48 hours. This will kill any mites/insects/parasites. Step 2: Wash them in hot, soapy water. I use the Blue Dawn dish soap that is used to clean oil off the feathers of birds affected by oil spills. It cuts through oil and dirt but does not harm the feathers. Step 3: Gently towel dry each feather, using a swiping motion in only one direction (quill to tip). Step 4: Blow dry each feather with a hairdryer on medium/hot setting. This returns them to their natural, fluffy state. It is a time consuming process, but worth it to ensure your feathers are properly cleaned. Final Step: I always wash my hands one more time when I am finished with the process. Hope that helps everyone! :)
Also, I have found that bleach and borax will start to "eat through" the feathers. The cornmeal mixture technique is used for drying body parts out/preserving limbs (think taxidermy) but not necessary for feathers.
I was taught to put them in the freezer for 1-2 weeks (to kill the mites) then wash them in baby shampoo and let them dry naturally and run them through your fingers to replace the natural oils.