I macerate all my skulls with nothing but water, at temps around 85. They take about a week or so and come out nice and clean. I then degrease with some blue dawn at around 113 degrees. My problem is, when they go into the degreaser they are fairly clean and white but after a few weeks in the degreaser they are disgustingly brown and never seem to fully whiten when peroxided. I change the water every week. Not sure if this is common or if I’m doing something wrong. Thanks in advance for help.