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NOTE ON COBALT STAIN IN WHITE WARE BODIES
Author(s) -
Watts Arthur S.
Publication year - 1921
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1921.tb18682.x
Subject(s) - stain , glaze , cobalt , chemistry , mineralogy , metallurgy , materials science , ceramic , staining , medicine , pathology
Faulty methods of adding cobalt. —Cobalt oxide or directly added cobalt sulphate frequently causes a blue‐gray cast when the body is hard fired. Correct preparations of stain from cobalt sulphate. —To 750 ounces of pure water add 15 ounces pure cobalt sulphate (CoSO 4 + 7H 2 O) and stir until dissolved. Then add 7.5 ounces of carbonate of soda (Na 2 CO 3 ) and stir thoroughly. Adding stain to body. —Ball clay must be thoroughly blunged with body before adding stain. If used in a casting slip, add the stain as a part of the casting solution. Proportions stain to body. —For a body containing 10 per cent ball clay add 75 ounces stain solution to each 1500 pounds body, i. e. , ½ ounce stain for each 10 pounds body. For bodies with higher ball clay content increase the stain addition in the same ratio up to 15% ball clay. Stain in glazes. —Add 10 ounces stain to each 100 pounds dry glaze batch when same is thoroughly wet in mill. For glaze high in lead, the amount of of stain required is increased.