Lado has newly introduced sky-blue series photosensitive liquids, which have especially perfect development performances in poor alkali aqueous. PS plates coated with these photosensitive liquids could be developed cleanly in 1% Na2SiO3· 9H2O aqueous in 45 seconds, so that dilute developer, which is more environmental friendship, could be recommended to use. Moreover the liquids could be used for eliminating contamination of PS plates.