>I was told that the black is prefered by the queen to lay eggs in as it has better heat retentive properties, and more resembles older comb.
I donâ€™t personally think there would be any more heat retentive property from black plastic foundation than there would be from white plastic foundation inside the hive. If both were sitting in direct sunlight, that could possibly be said.
As far as resembling old comb, bees prefer old comb because it has had brood raised in it which darkens the comb. How can bees tell the difference between black plastic and white plastic foundation inside a dark hive?