Ah,
We've seen quite a few cases where the top layer of the scales flaked off individually even when just using oil based cremes - it may be a specific type of oil that causes it but it definately does happen on occasion.
I wonder if it is a vegetable or mineral oil specific problem?
Since the water bath does the same thing and is a lot easier to clean off it seemed an easier fix to me.
Touch wood I haven't had to deal with mites since the mid to late 90's **taps head**
dr del