Gink has a specific gravity of only .77% that of water, which means it's lighter than water. It is a liquid emulsifier that permeates deep into the body material of dry flies. It will either coat sythetics or penetrate fur or feather.
Gink is a light paste that turns to a liquid at skin temperature. Upon coming in contact with cold water it returns to a clear, unseen, invisible gel that keeps water from making your dry flies or streaking streamers, wet. Flies stay dry for the normal useful life of any and all dry flies astream.