An important first step that I take for granted and didn't mention was a thorough cleaning before placing the item in peroxide. Always thoroughly clean any pot before bleaching. First, wet the pot thoroughly and brush lightly to remove dirt. Next, I use a spray cleaner like Mean Green or Thunderbolt. This is particular true of bisque finishes like Wedgwood, Radford Jasperware, Ecanada, and Bement.
Some restorers use the cleaners for false teeth and claim great results.
I tried one of them 20 years or so ago, wasn't pleased and never tried them again. Just last week at the Association of Restorers convention at San Jose, someone told me they were using false teeth cleaners and were very pleased. Most of us use hydrogen peroxide. Do not use Clorox. It will go into any crazing and will continue to leach a white powdery substance out of the crazing for months.