The material that you adhere to your terracotta pot to create the mosaic design, also called tesserae, can become scratched or otherwise marked if not protected by sealant. Sealing mosaic terracotta pots is an essential task as it not only protects the tesserae, but the grout, as well. Seal your mosaic terracotta pot after you have adhered the tesserae to the pot with mortar and applied grout on top.
Go outside, if possible. Sealant typically produces strong fumes which can cause headaches, dizziness and other similar symptoms. Going outside typically provides enough ventilation to prevent these problems from occurring. If you can't venture out, apply the sealant in a well-ventilated environment.
Pour the sealant into a small container. Dip a small paintbrush, about 2.5 cm (1 inch) wide or smaller depending on the size of your piece, into the sealant. Wipe the brush on the edge of the container to remove any excess sealant.
Apply a thin layer of sealant to the pot in the same manner as you would apply paint. Start at the top and work your way down towards the bottom. Add more sealant to your brush as needed.
Apply a second coat of sealant after you've allowed the first coat to dry for 10 to 15 minutes. Buff the pot with a soft cloth once the sealant has dried, to add shine to the pot.
Apply new sealant to your pot every two or three years for continued protection. Bring your mosaic terracotta pot indoors to protect them, if you live in a location that receives lots or rain or snow.