POWERHOUSE COLLECTION

De Laval cream separator, c.1900

Object No. 85/563

Cream separators were machines used to separate the fatty content of milk from its watery constituents in order to produce cream. The separator used the principle of centrifugal force by rotating milk at high speeds inside a steel bowl. The heavier parts of the milk passed to the outside of the bowl leaving the lighter cream to collect in the centre. The main parts of the separator were the bowl, a series of separating discs within the bowl, a cream regulating screw and passages to and from the bowl. Milk was fed into the rapidly spinning bowl and picked up motion from the separating discs. The bowl needed to be properly balanced to prevent vibration and the machine secured to the floor or bench. It was lubricated with special oil which was changed regularly. Various methods were used to operate separators including the rotation of a hand crank (the hand method), steam and internal combustion engines and later electricity. Butter making on Australian farms was widespread on the 19th and until the mid. 20th century. Developments in refrigerated transport in the late 1870s and 1880s boosted the production of butter and other dairy products. Milk was "separated" to retrieve the cream which was then beaten to make butter. The cream from 25 litres of milk is needed to make 1kg of butter. Before the mechanisation of separating with a cream separator, preparations for making butter had to begin 72 hours before churning. Milk was poured into a settling dish, a large shallow pan either tin or earthenware and left over night. The cream separated from the milk and was skimmed off with a skimmer or fleeter, a shallow perforated saucer on a handle. The cream was then covered with muslin and left to ripen for 48 hours before churning. By the 1890s the cream separator had been devised which replaced the overnight setting of milk. Milk was warmed, to help separation, then poured into a tank at the top of the separator. The milk passed into a chamber fitted with a float and then through a strainer into a chamber which revolved at great speed. Centrifugal forces caused the heavier skim milk to fly to the outside and the lighter cream stayed near the centre. The skim milk and cream was channelled through two different spouts. Cream separators came in a variety of sizes and were operated by hand, horseworks and power driven from engines. The small hand-operated models could separate 10 gallons of milk per hour and were used on farms with only a few cows to provide cream for the home and butter for making. The engine powered separators could separate from 75 gallons to 120 gallons of milk per hour. Margaret Simpson Curator, Science, Technology and Industry June 2014