While reading about fining wine, I found it interesting (still do) that Egg Albumen amoung the agents used. Prior to this the only place I'd heard of it's use was in violin finishing.
As a sealant / hardener, the egg white is beat stiff then placed in a strainer over a bowl for 24 hours. The clear liquid that seeps off is what is used. The varnish can be stripped from a violin that has been sealed in this manner but the Albumen seal remains, this is due partly to the material having soaked into the wood.
As to wine making, it would appear the whole albumen is used for fining. I've seen powdered egg albumen on a number of beer / wine making web sites, this is what I would use for fining rather then raw / wet egg white where I to use it at all.
Anthony