I'am having trouble with the stock-clarification process. I do the beaten egg-white and crushed egg shells thing and have also added chopped tomatoes. I bring to a simmer, remove from heat, and let cool. The "raft" forms with no problem. When I attmpt to move the raft aside or poke a hole in it, everything starts to break up and the impurities filter back into the stock. What am I doing wrong? Can some of you hounds with expertise in this area please help out this novice?