How do you remove uric acid crystals from toilet cassette in a caravan?

We are assuming your toilet cassette has a ceramic bowl and perhaps a stainless steel cassette. If your urine stain is in the bowl your need to shut off the water and saturate with urineFREE. Let it air dry and then flush and see how much you got. Old stains may take more then one application. If the uric acid has corroded the bowl, sometimes replacement is the only solution.

urineFREE will also work well refreshing the cassettes after dumping the waste.