Solids were stable and did not show visible signs or changes in their spectra after being kept at room temperature for over 60 days. The absorbance at the maximum absorbance wavelength remained unmodified.

This precipitate is not suitable for a pigment until it is filtered, dried, crushed, heated to a high temperature and quenched in cold water. The second heating in a muffle furnace at 725 °C produces crystals of the right optical size.

Method of producing improved lithopone