| 摘要 |
The chalk is coated for strength and resistivity from powdering. Anylose 15-30 vol.%, anylopectin 15-30 vol.% and a glassy material 7-25 vol.% are diluted with water of 15-63 vol.% heated slowly, and cooled slowly. The chalk is coated by dipping it into the diluted solution for 5-10 minutes.
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