Abstract: The invention describes a solvent mixture for photohardenable compositions, which includes(a) a first component having(i) a first constituent of(aa) a polar solvent of the formula R-OH, wherein R is a H or alkyl, or(aa') a monoalkylether or an alkylether ester of a glycol and constituent of(ii) a second an organic solvent having a boiling point in the range of from about 60.degree. to 160.degree. C. and comprising an aliphatic ketone, an alkanoic acid alkylester, a hydroxyalkanoic acid alkylester or a cyclic ether,in quantitative proportions selected to form a homogeneous mixture, andb) from about 0.1 to 8% by weight, relative to the total solvent mixture, of another solvent, the boiling point of which is higher than each individual boiling point of the constituents of the first component (a). The solvent mixture is used to obtain coating solutions layers which have a higher photosensitivity than corresponding layers prepared without the addition of component (b).

Abstract: A process and apparatus for developing a latent electrostatic image on an electrophotographic copying material by means of a toner dispersion. An infeed roller applies the toner dispersion to the copying material, and, downstream thereof, a distribution roller acts on the surface of the copying material. To solve the problem of reproducing fine white indicia, such as thin white lines, on a black background, a voltage, having the same polarity as the surface charge of the latent electrostatic image on the copying material, is applied to the distribution roller. Squeegee rollers downstream of the distribution roller effect removal of unused toner. Toner, which adheres to the distribution roller during application of voltage to the distribution roller, is sprayed off and recovered for recycling, the spraying agent being toner dispersion.

Abstract: Disclosed is a process and apparatus for separating aspherical particles from spherical particles in an admixture thereof, preferably in the preparation of a particulate carrier material for two-component developer systems for electrostatic copy devices. The process comprises directing the mixture of particles onto a surface which is inclined with respect to the horizontal; producing a relative velocity between the inclined surface and the mixture of particles, the velocity having a directional component transverse to the steepest inclination gradient of the inclined surface; and collecting a portion of the mixture of particles in a zone of the inclined surface wherein predominantly spherical particles have accummulated as a result of their greater tendency to roll in response to the relative velocity than the aspherical particles.