| 摘要 |
A layer of limed rosin sensitized with a photoactive dye or a photosensitive organic polyhalogen compound is normally hydrophobic, but is rendered soluble in weakly alkaline aqueous solution upon exposure to light. When over-coated upon a hydrophilic base sheet these limed rosin materials provide aqueous-developable, positive-working lithographic printing plates, or when coated upon film layers soluble in aqueous solutions they provide for aqueous-developable reproduction sheets by means of etching processes.
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