The reason why people stopped using Hob to keep water in the shower is because the are notorious at letting water in. You can use Remedial Membranes, Clear Waterproofing Membrane. You will waterproof to the shower screen so it will create like a clear tray in the base of the shower and you can make it to your existing finish; gloss, satin or matte so that it is hard to pick the membrane on the tile.
