Extremely or especially fine.Some recipes call for superfine sugar because it dissolves easier.
1726, Twelve years ago they made only course Cloth, but now they weave superfine, and fine Cloth.
Of a very high or pure grade.
1799, The laboratory; or, School of arts, With respect to the matter of the medals, we must observe that, for the generality, they are made of pure gold or silver, without the allay of any other metal. Some indeed are struck on superfine copper.
1932, August 26, Combination Dinner Set Of 121 Pieces for 27.50, This set contains 97 pieces of superfine china and 24 pieces of etched Belgian glassware