I went out for a day and poor DCat 1 was shut in the spare room. I found one wee (on a folded blanket that went in a boil wash PDQ) but have just found wee 2 on the corner of the bed. It caught the corner of the duvet (drying on the line after a boil wash) and the waterproof mattress cover (currently on a boil wash).
Problem is that the waterproofness was only on the top and the corner of the mattress whiffs a lot bit so I suspect some cat wee went down the side and into the mattress material but not actually inside the main part of the mattress. It's a fairly new matress, only slept on a few dozen times so if it can be rescued I'd like to.
So far I have poured half of a bottle of upholstery cleaner/ de-odourer through and scrubbed at the material throughly. It's drying a the moment but there is a bit of eau-de-chat about. Any other ideas apart from burning the room out