Slate is a beautiful surface that can give your bathroom shower walls a more natural and rich look. The only problem is that because slate is highly porous, it can be ruined by water easily. If you want to put slate shower tiles in your shower, you'll need to seal them to keep them looking their best and to keep them from being damaged. Sealing slate shower tiles is an afternoon job, but it can help keep your shower tiles looking great for years to come.
Use a wash cloth to brush any dirt or dust off of the shower walls. You want them to be very clean, because whatever the sealant touches, it will seal, and you won't be able to clean it off.
Wait for the walls to dry completely.
With a sealant specified for waterproofing tubs and showers, brush on a coat. Work in a two-by-two tile area, and make sure you stroke on an even coat.
Use the paint brush to dab the sealant deep into grout lines.
Let the sealant dry, as according to manufacturer's instructions. When the first coat is dry, you can then apply the second coat in the same manner.
Apply at least three coats for maximum protection.