If you want to reseal your wet room shower tray, make sure that it's completely dry before you start. Then mix up a relatively thin paste, using sealant powder and water. Apply this with a pallet knife, smoothing it out evenly across the base of your shower tray.

Of course, you can also purchase watertight sealant in tubes, and simply reseal the shower that way. You may need to remove any previous sealant to ensure a clean, consistent and watertight seal.