I use Makers Magic to waterproof and seal. These clay pots have been left natural on the bottom to help with evaporation for succulents. I also coat the inside of the pot where the outside was painted, so that water does not seep through and bubble the paint. The painted area outside is sealed with Makers Magic, then vinyl or waterslide decals are applied, then sealed again. I use the pots outdoors so I want to protect the designs from the heat, humidity, and rain in Southwest Florida.