Abstract: Diazotype material having enhanced water-wet properties and especially suitable when imaged for being drawn or written upon, and for use as an intermediate original, is made of a support such as a transparent polymeric film carrying on one of its sides a light sensitive diazo layer formed of a dispersion of a light sensitive diazonium compound and a large amount of amorphous hydrated silica particles having a bound water content of at least 50% by weight in a polymeric binder consisting essentially of a 20 to 45% hydrolyzed polyvinyl acetate which preferably is a product of partial hydrolysis of a PVAC having in ethyl acetate at 20.degree. C. a Heoppler viscosity of 100 to 800 mPa.s. The weight ratio of the hydrated silica to the partially hydrated PVAC in the layer typically is in the range of 2:3 to 3:2. The support advantageously carries on its other side a light-pervious drafting layer formed of a dispersion of a silica filler in a partially hydrolyzed PVAC the same as that required for the diazo layer.

Abstract: A composition and process for developing diazotype material utilizes a developing liquid comprising a buffered, aqueous solution of an azo-coupling component having a pH between 5.5 and 8 and, as an additive compound, sorbic acid, an alkali metal salt, ammonium salt, or magnesium salt of sorbic acid or mixtures of the same. The process produces a clear copy image more quickly than a process in which the developing liquid does not contain the additive compound and, when the azo-coupling component is a mixture of phloroglucinol and resorcinol, forms a neutrally black image. The additive compound is added in an amount of 10 to 80%, and preferably 30 to 60%, by weight, of the maximum amount soluble in the solution at room temperature.