Under-glaze — Decoration painted or printed on to the ceramic surface prior to the application of a glaze.
unslaked lime — Chemical compound, also known as quicklime or burnt lime, calcium oxide (CaO). It is white, caustic, alkaline, crystalline, solid at room temperature. By contrast, slaked lime is calcium hydroxide, Ca(OH)2.
Up-draught kiln — An intermittent kiln in which the combustion gases pass from the fire box at the bottom through the firing chamber and then through one or more openings in the roof.
