I started to do some actual prints today and found that my vandyke solution had a fairly large number of green flakes in the bottom. I have not seen this before and don't remember reading anywhere about flakes. I'm guessing that it must be some iron precipitating out of the solution?
The solution was made in November 2007 and has been kept wrapped in black bag in the darkroom. It has not been refrigerated but the room never gets much above 70 degrees.