From what i understand this Developer #40 creme solution is a bit different then the Retirbright method.

basically with this method all you need is this product , a paint brush, and the sun, for a couple hours.

then rinse and Yellow be gone.

one of my old buddys Jason,,, (aftermac)

he has an Obscene Vintage Mac collection.   Him and his wife caught wind of this simplistic method, (Developer #40) and

have been going through his computers one by one with, from what I understand to be 100% success.

http://www.macobserver.com/tmo/article/tmo_workspaces_jason