There appear to be two different methods of manufacturing the various signals, with the exception of the smoke signal. In the first instance the use of a briquetting machine compresses the illuminating charge into the desired form, requiring slightly different assembly than in the second or older method of preparing the light signal, which is the method customarily in use. Both of these methods of manufacture will be described.
A completed signal light consists of a briquette composed of the illuminating composition, a wrapper, wet prime, paper disk, quick match, knot socket, and tie string.
The composition from which the briquette is molded consists of -
Meal powder (black).......................
These component parts of the composition are mixed in the manner previously described, namely, by hand mixing in an open tray and successive screenings through a sieve in order to insure a thoroughly homogeneous mixture.
The above composition is made up in unit batches of 24 pounds each, which are moistened with a binder before briquetting. The binder used consists of a shellac-and-alcohol mixture in which the shellac has approximated twice the weight of the alcohol. The usual procedure is to add 1 3/4 pints of this binder to each 24 pounds unit batch.
Fig. 42. - Briquette plunger and mold.
The composition is first loaded into a mold which is shown in figure 42.
In the foreground of this figure is shown the rammer.
Figure 43 shows the operator putting the charge in by hand, the mold being filled to the brim. The dimensions of this mold and rammer, which is made of Tobin bronze, are shown in figure 44.
Figure 45 shows the Arbor press which is used to form the briquette.
Figure 46 shows the method of exerting a uniform hand pressure in successive operations.
It is usual to have a lever supporting the base block of such a length that 113 pounds at one end will support a weight of 1,300 pounds at the other or block end. A pressure of 1,300 pounds is that used for briquetting.
Fig. 43. - Loading charge into mold.
Figure 47 shows the briquette after it has been forcibly ejected from the mold, which is 2 1/4 inches high by 1 3/16 inches in diameter.
Fig. 44. - Dimensional drawing of mold and plunger.
The briquettes are then dried in a drying room at a temperature of 100° F., remaining there for two or three days. This must be a properly ventilated room in order to carry off the alcohol fumes.
The wrapper consists of a strip of 30-pound Kraft paper 2 3/4 inches wide by 8 inches long. A coat of paste is applied to the wrapper, which is formed around the briquette, flush with one end.
A coating of wet prime is applied to the bottom of the briquette, consisting of a paste of meal powder and water.
Fig. 45. - Arbor press.
A tissue-paper disk approximately 2 1/4 inches in diameter is placed over the wet prime and pasted to the side of the briquette, and on top of the disk is applied a strip of wet prime into which is imbedded the quick match.
The quick match is a six-ply match cut in length 2 1/4 inches, the ends being carried down over the edge of the briquette and firmly tied with jute string, as shown in figure 49.
This is a piece of unbleached muslin 2 1/2 by 7 inches. It is given a coat of paste and bound around the top of wrapped briquette, covering about 1 inch. This is used to form a socket in which to attach the end of the parachute strings.
Fig. 46. - Arbor press showing lever and weights.
The asbestos cord by means of which the briquette is attached to the parachute is inserted in the knot socket, a knot having been previously tied in the end of the cord. The tie string is of jute, cut to a length of 8 inches, which holds the muslin crimped tightly about the cord and makes a lock for the knot.