I'm getting into 4x5 sheet film processing at the moment and have done a bit of tray processing, just doing one sheet at a time though. I'm worried that processing more than one sheet in a stack will end in scratches on the film so slosher trays sound and look like a good alternative. The only place that seems to sell sloshers (that I can find) is Photographers' Formulary, as I'm based in the UK I was hoping that there was a shop over here selling them. Does anybody know of such a place?