Rinse terra cotta saucer to remove dust and debris. Allow to dry overnight. Seal all saucer surfaces with a terra cotta sealer. Allow to dry at least two hours before gluing on mosaic pieces.
Using the plastic knife, apply a thin layer of adhesive to the back of each tile. Press the tile, adhesive side down, to the saucer. (I find it easiest to start gluing from the outside of the pattern and then work my way in.) Allow no more than 1/4 inch between the pieces and try to keep the distance the same between all the pieces. This will add strength to your bird bath and will be more pleasing to the eye.