Popular Science Alonthly
��Photographic Printing Masks Easily Made
PRINTING masks are easily made from the black paper found in all negative boxes. After determining the size of opening desired, a rectangular mask is cut as follows:
Take a sheet that is large enough to fully cover the negative and fold it two \va>s to make four thicknesses. Make the folded edges exactly even with each other — they will then be perfectly square. Lay off at right angles to the shorter fold, one-half of the longer dimension of the
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� ��— I CUT AND j-PASTED ON
It may be improved by moistening be- tween two damp blotters in the press till the folds disappear. A number of modified corners may be devised for use with such rectangles by the aid of the red paper seals sold by stationers, or a little ingenuity will enable the operator to cut these designs from the black paper with scissors.
Oval, elliptical, or circular masks, can be cut with shears, after laying out one- fourth of the figure as shown in the illustra- tion. Finally, any special shape, symmetri- cal about one axis, can be laid out with pencil on a doubled sheet (the fold forming
���RED PAPER DISK GUMMED ON
��CORNER OF MASK
��ELLIPTICAL MASK MADE WITH ONE CUT OF SHEARS
��FANCY CORNERS AT ONE CUT
����KNIFE FOR CUTTING MATS AND MASKS
��All patterns for making cut-outs and fancy comers for photographic masks are easily formed with a four fold paper, cutting all the quarters at the same time with a pair of sharp scissors
��opening desired, and mark, preferably by nicking the folds with the point of a sharp knife. Do the same with one-half of the short dimension on the other folds. Lay a straight edge (an old negative will do), on the nick. Repeat the measurement to the straight-edge at the outer edge of the folded sheet. Nick this with the knife. Draw a fine pencil line between the two nicks. Repeat with the remaining measure- ment. Cut along the straight edge from the pencil line to the nick. Cut at right angles along the pencil line from the first cut to the nick. When opened up, a true rectangle of the required size is obtained.
��the axis) and cut with shears. The results, after a little practice will be absolutely satisfactory, and will be endless in variety.
For larger sizes, the various geometrical figures can be laid out with accuracy by the use of drafting instruments. Directions for describing all ordinary geometrical figures can be found in almost every engineer's hand-book.
To describe an ellipse, however, with little trouble, requires only a rule, two jiins, a piece of string and a pencil. Having determined the length and width, draw two axes at right angles. The intersection is marked A in the diagram. From B lay off