Berlin blue prodn. - by forming ferrous ferrocyanide at a specif. temp. converting it to berlin white and oxidising

摘要

Berlin Blue is made by reacting Ca or Na ferrocyanide with a Fe (II) salt at a pH of 7, converting the acid ferrous ferrocyanide to Berlin White with (in)organic K salts at pH 1-6 and oxidising this Berlin White as per the parent patent wherein the acid ferrous ferrocyanide is formed at 25-60 degrees C, esp. 40 degrees C. The softness is improved.