Reproducing engineering data

Claim 1

A PROCESS FOR PHOTO-MECHANICALLY REPRODUCING ENGINEERING DRAWINGS FROM LOFTS, MASTER DRAWINGS AND THE LIKE, WHICH COMPRISES COATING A SURFACE OF A SHEET OF GLASS WITH A VERY THIN EMULSION OF THE AMMONIUM DICHROMATE TYPE WHICH IS IS TEMPORARILY PHOTO-SENSITIVE, PLACING THE EMULSION SIDE OF SAID SHEET OF GLASS IN FACE CONTACT WITH THE DRAWING TO BE REPRODUCED, EXPOSING THE EMULSION WHILE STILL SENSITIVE TO LIGHT TRANSMITTED THROUGH THE GLASS AND REFLECTED FROM THE DRAWING FOR A RELATIVELY LONG PERIOD OF TIME, WHEREBY THE EMULSION CONTACTING THE LINES OF THE DRAWING IS RENDERED WATER SOLUBLE AND THE REMAINING EMULSION WATER INSOLUBLE, ROLLING UP THE EXPOSED EMULSION WITH ETCHING INK, REMOVING THE WATER SOLUBLE PORTION OF THE EMULSION AND INK COVERING SAME TO ACCURATELY REPRODUCE THE LINES OF THE ORIGINAL DRAWING IN THE FORM OF IDENTICAL WIDTH CLEAR LINES ON THE SURFACE OF THE GLASS, LOCATING THE NEGATIVE THUS FORMED IN FACE CONTACT WITH A PHOTO-SENSITIVE SURFACE PRESENTED BY A VERY THIN EMULSION COATING ON A SHEET OF TEMPLATE STOCK, EXPOSING SAID LAST MENTIONED PHOTO-SENSITIVE SURFACE TO LIGHT PASSING THROUGH THE CLEAR LINES OF THE GLASS NEGATIVE TO PRODUCE, AFTER PROCESSING SAID PHOTO-SENSITIVE SURFACE, AN ACCURATE INK LINE REPLICA OF THE ORIGINAL DRAWING ON THE TEMPLATE STOCK, REMOVING ANY INK LINES DESIRED FROM THE LAYOUT THUS PHOTOGRAPHICALLY TRANSFERRED TO THE TEMPLATE STOCK, COATING THE SURFACE OF THE STOCK INCLUDING THE INK LINES WITH SHELLAC, SUBJECTING SAID SHELLACKED SURFACE TO A SOLVENT OF A NATURE TO REMOVE ALL INK LINE FORMATIONS FROM SAID SURFACE TO EXPOSE THE SURFACE OF THE MATERIAL FORMING SAID TEMPLATE STOCK, SUBJECTING SAID SURFACE TO AN ETCHING SOLUTION TO PRODUCE ETCHED LINES TO A DEPTH OF TWO TO THREE THOUSANDTHS OF AN INCH AND IDENTICAL IN WIDTH TO THOSE OF THE ORIGINAL DRAWING, AND THEREAFTER FABRICATING THE TEMPLATE STOCK IN ACCORDANCE WITH THE ETCHED LINES FORMED IN THE SURFACE THEREOF.