GB167298A - Improvements in and relating to etching processes and apparatus for use therein - Google Patents

Abstract

167,298. Lucas, H. C., and Lucas, A. J. May 6, 1920. Etching. - Etching- apparatus of the kind in which the surface of the plate &c. to be etched is supported in an inverted position and in which the etching- fluid is projected upwards thereon in the form of spray produced by compressed air, comprises a closed ventilated chamber, a lid adapted to be clamped on the chamber, and suction devices on the lid for supporting the plate &c. to be etched. The air passages of the sprayproducing nozzles, which are immersed in the etching-fluid, are interrupted by a transverse chamber below the level of the fluid, the air issuing from the lower portion of the air passages forcing the layer of fluid in said chamber through the upper portion of the air passages in the form of a fine spray. As shown in Fig. 1, the lids b of the etching-chambers a are carried by vertically hinged brackets e and are clamped in position by screws d. The plates l to be etched are supported by suction plates f provided with suction bulbs h. The spraying nozzles k immersed in the etching-fluid in are connected by pipes n to the compressed air supply-pipe o, other pipes controlled by cocks q being adapted to admit air to the upper part of the etching chambers for expelling evolved gases &c. along pipes p to the conduit r, fitted with a draining-chamber s. Fig. 3 shows the construction of the spraying-nozzles. Compressed air is admitted by the pipe k<6> to an annular space k<5> and issues therefrom through a series of passages k<4> into a thin annular space k<1> which is below the level k<2> of the etching-fluid. The fluid in the space k<1> is thereby atomized, and blown through the upper passages k<8>. The nozzles may have an aperture k<9> so that the surrounding atmosphere above the fluid may be associated with the induced fluid, and a deflector k<10> may be provided.