For cutting out ovals, Robinson's trimmer is an excellent adjunct to the mounting-room, and in this case ovals stamped out of sheet brass are used as guides.
Fig. 29.
The figure will show the action of the trimmer. The small wheel is the cutter, and, being pivotted, it follows the curve against which it is held. It is better to cut out prints with this trimmer on sheet zinc in preference to glass, the edge of the wheel being kept sharp for a longer time than where the harder glass is used. To use the trimmer, the print is placed on the sheet of zinc, the oval mask (or square mask, with slightly rounded corners) is placed in position on it. The wheel of the trimmer is brought parallel to, and against, the edge of the mask, the handle being grasped by the right hand, the thumb to the left, and the fingers on the right. A fairly heavy downward pressure is brought to bear on the trimmer, and at the same time the wheel is caused to run along the edge of the mask. The cut should be clean, and the join perfect, if proper care be taken. It is desirable to practise on ordinary writing paper before it is taken into use for prints. Square masks with very slightly rounded corners can be used; the smaller the wheel, the less curved the corners need be. It will be seen that there is a limit to smallness of the wheel used, since, if too small, the stirrup on which it is pivoted would rest upon the mask. The larger the wheel the easier is the cutting.
With larger sizes than the carte or the cabinet, mounting may often have to be delayed, since it is easier to keep a stock of unmounted prints (say landscapes) unmounted than it is when they are mounted. In this case the prints should be put away as flat as possible. The plan of drying we have indicated takes out the "curl," but even then they will not be flat enough to be handily put away. We therefore recommend the practice of stroking the prints. A flat piece of hard wood, about 1 foot long and 11/2 inch broad, and the thickness of a marquoise scale, has its edges carefully rounded off. The print is seized by one corner in one hand and unrolled; the face of the print is brought in contact with a piece of plate glass. The "stroker," held by the other hand, is brought with its rounded edge on to the back of the print near the corner held by the first hand. Considerable pressure is brought upon the stroker, and the print is drawn through between it and the plate. The print is then seized by another corner and similarly treated. By this means a gloss is put upon the print, and the creases and cockles are obliterated. The print is now ready for trimming.
It is well to have a square of glass with true edges cut to the size of the pictures. The prints should be trimmed upon a sheet of plate glass, a sharp penknife being used to cut them. A rough test for ascertaining if the opposite sides are equal is to bring them together, and see if both corners coincide.
It may sometimes be found useful to cut out a print into an oval. The following method for tracing any ellipse may be employed:—On a thickish piece of clean paper draw a line A B, making it the extreme width of the oval required. Bisect it at O, and draw D O C at right angles to A B. Make O C equal to half the smallest diameter of the ellipse. With the centre C and the distance O B, draw an arc of a circle, cutting A B in E and F. Place the paper on a flat board, and at E and F fix two drawing-pins. Take a piece of thread and knot it together in such a manner that half its length is equal to A F. Place the thread round the two pins at E and F, and stretch it out to tightness by the point of a lead pencil. Move the pencil guided by the cotton, taking care to keep it upright. The resulting figure will be an ellipse. Modifications of this figure may be made by making a second knot beyond the first knot, and placing the point of the pencil in the loop formed. When the figure has been traced in pencil on paper, it should be carefully cut out with a sharp penknife, and placed on the print which is to be trimmed into an oval. When so placed, a faint pencil line is run round on the print, and the cutting out proceeds either by scissors or penknife.
Fig. 30.