Harper's indoor book for boys

by Joseph H. Adams

From a solid piece of lead one and a half inches long, three-quarters of an inch wide, and one and a quarter inches deep, cut a lug, with a knife and file, having two projecting ears as shown at C in Fig. 8. The lower part is half an inch in diameter and three-quarters of an inch long. With a hot iron burn a hole in a cork so that the lower end of the lug will fit within it, as shown at D in Fig. 8. With a small drill bore a hole in the end of each ear. These holes should run through towards the middle of the lug, taking care, however, not to bore too far, since the holes must not meet. Bore two holes up through the lower part of the lug so that each will meet one of the holes bored through the ears, as shown by the dotted lines at A in Fig. 8. By this construction the air forced through a tube connected with one ear travels through that ear and down into the bottle; then up through the other hole and out at the opposite ear, where another tube is attached that leads to the platinum-point. The end of an old syringe can be used for the supply bulb, and for the pressure bulb there is nothing better than the inner bladder of a football, if it can be provided with an extra tube so that air may be forced in at one end while it is escaping at the other. This rubber balloon can be inflated to twice its normal size if care is taken not to blow it up too large. As a precaution against its destruction, it would be well to make a protective net from cotton string with a small mesh. This is easily done by making a wire hoop the diameter of the bladder when blown to its safe size; then loop cotton string over it, as shown in Fig. 9, and tie the knots forming the meshes as shown at the left side of the same drawing. Continue the work until a cylindrical net is formed about three or four inches longer than the size of the inflated bladder. With a draw-string the open ends of the net can be drawn together after the bladder is placed within it. The outlet of the bladder is connected by a rubber tube to one ear of the cork, and another tube leads from the opposite ear to the platinum-point and holder.

The holder is simply a piece of brass tubing at one end of which a coupling is made fast. This tube is pushed through a cork handle, or the covering can be made by burning holes through corks and slipping them over the tube, at the same time using thick shellac to act as a glue and hold the corks to each other and to the brass tube. The cork covering should be heavier near the point end, because the tube becomes hot from the superheated platinum-point. This handle should be three-quarters of an inch in diameter, and gradually tapered to half an inch at the back, as shown at Fig. 10. The brass tube should be five inches long and the cork handle about four inches in length. Half an inch of the tube projects beyond the back, or top, of the handle, and over this end a piece of rubber tubing is slipped. A complete outfit should contain three points—one sharp, one round, and one curved. These can be purchased at almost any art store, and should appear as shown in Fig. 11, A being the sharp point, B the round one, or grounder, and C the curved, sharp-ended point that is used for fine work and light lines in shading or background.

A good platinum-point can be bought for one dollar and a half; but better ones will cost all the way from two dollars to five. If a boy has points B and C in his outfit, he can do some very good work; but should it be possible to have one only, then the curved point C should be the choice, since with that tool almost everything can be done.

The principle of the gasolene pyrographic outfit is very simple. The reservoir-bottle is filled half full of gasolene, or benzine (62°), which can be had at a paint store for twenty-five cents a gallon. The union-cork stopper is then pushed down, and the platinum-point screwed in place at the end of the handle. Light the spirit-lamp and hold the platinum-point in the flame until it is cherry-red; then squeeze on the supply-bulb and fill the pressure-bag. The air forced through the first section of rubber tubing goes down through one hole in the cork, picks up some gasolene vapor from the reservoir-bottle, and passes along the second section of tubing to the point, where it escapes through a very small hole at the side. Directly the vapor reaches the flame it ignites, and the hot point is kept in its heated state so long as the pressure of the bulb forces the gasolene vapor out through the hole.

Do not bear hard on the wood when working. The heated metal will char the wood easily if gentle pressure and several strokes are used. Points A and B (Fig. 11) can be used on all sides and on end, but point C should be used only on its curved edge, as shown at A in Fig. 12; never as shown at B.

When both hands are needed for the work of holding the material and tool, a convenient foot device can be made, as shown in Fig. 13. This is a pressure-jack made from two boards, the upper one being cut and hinged, as shown in the drawing. The boards are twelve inches long and three inches wide, the short end of the top one being attached to the bottom plate with glue and screws. The wood should be three-quarters or seven-eighths of an inch thick, and it may be given a coat of shellac or varnish to improve its appearance.

If a constant supply of air-pressure can be had without the bothersome hand or foot bulbs, it makes it so much easier to master the art of pyrography.

Any ingenious boy who has a foot pump, such as are used for bicycle or automobile tires, can get an old boiler from a plumber and rig up a pressure-tank such as is shown at Fig. 14. A small pressure-gauge should be screwed fast on top of the boiler, and two outlets with brass cocks should be constructed out of one-eighth-inch gas-pipe, the fittings being purchased at a gas-fitter’s or a supply house. By means of the pump compressed air can be stored in the tank, and the pressure will be registered on the gauge. Twenty to twenty-five pounds will be quite enough pressure for an old boiler, although sixty pounds is the standard to which most of them are tested when new. The advantage of the two outlet-pipes will be appreciated when working, because each can lead to a different sort of point, and this will save the time and bother of changing points frequently for different parts of the work.

The Practice of Pyrography

Basswood, deal, and white-wood are the material most commonly employed for this work, since the grain is close and the color even. Almost any soft wood, however, can be used, and the boy who has mastered the craft of carpentry can make his own boxes, frames, stools, chairs, and miscellaneous wooden objects, and then embellish them with designs drawn in lead-pencil, the lines of which it will be an easy task to follow with the hot platinum-point.