| 摘要 |
Projection and communication board, characterised in that it consists of a double-sided enamelled steel plate with an enamel undercoat, on which a second white enamel coat is laid on the writing side, which after annealing presents a roughness of:
and on which a third thin finishing coat is applied consisting of enamel powder, more than 90% of which consists of grains of less than 15 µm, and which after annealing presents a roughness of: |
