Another way to give it the half-round form is to file a groove into a stone, giving it the exact shape the pen is to have. Into this groove lay the piece of steel, put in a drop of vegetable oil, and polish with a steel instrument whose end resembles a broken but well-rounded nail. Use sufficient pressure, and the steel will gradually assume the desired shape.
Either of these methods may be used, according to preference. It is to be noted that the degree of roundness depends on the artist's need, one finding a well-rounded pen better, another preferring one not so well-rounded. The less the pen is rounded, the more it will resemble a brush when used, but the points will not spread so well without considerable pressure. The more they are hollowed, the stiffer are the pens and the more easily will the points spread when pressed.
After the pen is curved, it must be cut. With small, well-sharpened scissors cut a slit about one line in length into one end. Then cut away from the two sides as much as necessary till the point is sufficiently fine. Do not cut away too much at once, as the pen bends easily and then must be straightened out again, which demands especial skill. It is well to do the cutting from the point toward the sides.
A good pen must have both points very uniform, so that they touch perfectly and lie on the stone evenly in the position given them by the hand when working. The cutting alone will do this, but a small, very fine whetstone may be used to aid.
A newly cut pen is somewhat rough at times and cuts into the stone, thus gathering powder that hinders the work. This defect generally cures itself after a few strokes on the stone. Beginners generally spoil their pens by bending them every few moments. Then they must be straightened out, which demands practice and judgment. It cannot be described, because the bending may assume a thousand shapes. It may be mentioned, however, that the points must always touch, but must under no circumstances interfere, one being forced behind the other. It is good, sometimes, if one can see through the slit when looking backward from the point. Some even cut a tiny bit out of the middle for this purpose, but that demands great skill and extremely good scissors, as otherwise the opening will be too large, which will spoil the pen entirely.
The ordinary drawing-pens, which can be loosened or tightened with screws, can be used very readily for drawing lines, if their points are made from very good steel that can be ground very fine and thin. However, for much line-work, for instance the background of a picture which consists of lines hatched crosswise, it is better to use the other pens. The ordinary drawing-pens are too likely to catch a little dust or dirt between their points, and then will spoil the lines.
Of all work of the pen style in lithography, the most difficult is to draw very fine and even lines with a ruler. I have succeeded best by using a pen previously so cut or ground that both points touched in the position in which I was accustomed to hold the pen when guiding it with the ruler. It is evident that the pen must be held to the ruler on its side, so that the groove that contains the ink does not point in the direction of the ruler, but away from it. It is well if there is a tiny space in the slit, as it helps the free supply of ink.
II
CONCERNING BRUSHES
Brushes are used for various purposes, as to prepare the plates, cleanse, etch, etc. Here, however, we speak chiefly of the small brushes required for writing and designing. For this are used the very smallest and best miniature brushes, and they must be especially treated.