| 配方类型： |
INKS AND MARKING COMPOUNDS |
| 配方说明： |
Heat-Resistant Crayon |
| 配制方法： |
Crayons prepared in the following manner are suitable for marking crucibles which ae to be ignited at temperatures near 1000'C. (1832'F.).
Mix thoroughly 5 g. of powdered ferric oxide with 1 g. of calcium oxide in a mortar. Add, with continuous stirring, 20 ml. of molten paraffin.
Continue stirring until a paste of uniform consistency is obtained. Pour the suspension into a glass tube of about 5 mm. internal diameter (a broken pipette is satisfactory). Allow to cool. Pour boiling water over the outside of the tube until the bond between wax and glass is broken.
then push out the crayon with a glass rod. Warp the crayon in a spiral of thin, narrow paper strip and seal with a cellulose tape. Marks made with such crayons on fused silica and on both glazed and unglazed porcelain withstand repeated ignition at high temperature. |
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