The Colonial Sugar Refining Company Limited, in a letter of April 23rd, 1957 sought assistance is improving the efficiency of gypsum washing carried out by their subsidiary Brunswick Plaster Mills. The Companys main requirements were: (a) Reduction of the salt content of washed gypsum ex Nowingi to less than 0.1 per cent sodium chloride equivalent. (b) Increased washing efficiency to improve the colour of the plaster. In company with Mr. P. Haley, Manager of the Brunswick Plaster Mills, Senior Metallurgist Mr. P. Hosking visited the mining leases on 12th and 15th May, 1957 and the plaster mill at Brunswick on 16th May, 1957. This visit was made in order to study the problems involved and to arrange a test programme to determine what improvements could be made. Part 1 of this report covers the plant visits and makes suggestions regarding test work to improve operating procedure. Part 2 contains results of this test work and recommendations arising therefrom.