Using linseed oil and wax to seal terracotta tiles produces a warm look, but the tiles will need more maintenance than if you were to use a synthetic tile sealer. Consider whether you can perform regular repolishing before you use this traditional sealing method. After setting the reclaimed terracotta tiles on the surface with an adhesive, you need to apply a sealer to prevent grout from permanently staining the tiles. After grouting, you can apply wax polish to protect the tiles.
Dampen a clean piece of cloth or sponge with boiled linseed oil.
Use the cloth or sponge to wipe the top surface and side edges of the reclaimed terracotta tiles to apply the boiled linseed oil evenly. This first coat is usually the most difficult one to apply because the porous tiles absorb the oil quickly. Apply several more coats of the boiled linseed oil to the tiles until the tiles can't absorb any more oil. At this point, the tiles will be darker in colour. Let the tiles dry.
Mix terracotta grout according to the manufacturer's instructions, and use a grout float to apply it to the gaps between the reclaimed terracotta tiles. Use the grout float to scrape off the excess grout, and wipe the surface of the tiles with a damp sponge to remove any excess grout. Wipe the tiles with a sponge or a piece of cloth when a haze forms on top. Let the grout dry.
Apply one or two coats of wax polish to the surface of the reclaimed terracotta tiles. Wax polish comes in various formulations, including concentrated paste and ready-to-use wax. Follow the manufacturer's instructions to apply floor wax.
Wait until the tiles are completely dry before applying the sealer.
Applying a sealer while reclaimed terracotta tiles are still damp can lead to the formation of mildew within the tiles. The mildew will appear as black or white marks on the surface of the tiles. If this happens, you will need to strip off the sealer and use bleach to kill the mildew.