The kneading machinery is similar to that used in the manufacture of rubber. When it is desired to give to the mass of gutta-percha a greater degree of elasticity than is natural to it, I mix up and incorporate with it, while it is going through the kneading machine, either a portion of caoutchouc or a portion of sulphur, or portions both of caoutchouc and sulphur.
The following are good average proportions: about three parts caoutchouc for every six parts of gutta-percha, or one part of sulphur for every eight parts of gutta-percha, or two parts of caoutchouc, and one part of sulphur for every six parts of gutta-percha. When caoutchouc, however, is employed to increase the elasticity of the gutta-percha, a degree of heat, of not less than 150° Fahrenheit is necessary to effect the amalgamation of the two substances. The caoutchouc is most conveniently introduced into the machine at the same time with the gutta-percha, but the sulphur should be dropped into and upon the gutta percha from time to time, and in small quantities at a time. The gutta-percha takes up the other materials readily, and the whole are, at the end of the process, thoroughly amalgamated. Should it be desired to give any color to the mass, the requisite pigment or coloring matter is introduced in the same manner as the sulphur, and also in small quantities at a time. The coloring matter penetrates every part of the mass, and becomes perfectly amalgamated and identified with it. The gutta-percha may be also improved in smoothness, by incorporating with it some pulverized French or Turkey chalk, or other soft powder, adding it in same way as the sulphur, or should it be desired to make it rough, and abrasive, it may be mixed up with some ground emery, sand, or other hard substance, in a granular state.
There are other combinations in which the gutta-percha in its plastic state, intimately mixed or blended with other materials, as for example:—There may be added to the gutta-percha, while in the kneading machine, paper pulp, wood dust, leather dust, hair bristles, oakum, &c. (taking care when they are not in a comminuted state, to cut them up small) and compound fabrics will be thus produced very suitable for paring, roofing, sheathing, and other purposes.
APPLICATIONS IN STATE OF SOLUTION.
As before stated the gutta-percha may be dissolved in most of the essential oils, and by the application of a gentle heat, the patentee states that he prefers using for the purpose, rectified naptha, or rectified oil of turpentine. It may also be applied in a state of solution to rendering water and air proof, or cementing the various articles to which gutta-percha has been before stated to be applicable for these purposes in a plastic state, when sulphur imposed upon or between the surfaces of articles. It may be applied in this fluid state, to the saturation of cordage of all sorts, in order to increase its strength, and render it water proof, and as a size for stiffening silks, ribbons, and other fabrics. And lastly, it may be employed in this liquid state mixed with colors, for printing silk, cotton, leather, and other fabrics.
R. A. Brooman caused another patent to be issued, under date of March 27, 1845.
The invention comprehended under this patent is stated to have for its object the “the manufacture of a thread of great strength and durability, and perfectly water-proof, from the substance called gutta-percha, and the application thereof to the manufacture of piece goods, ribbon, paper, and other articles.”
The specification then describes the manner in which this object is carried out. The machinery is very simple. It consists of a die-box kept hot by steam, from the bottom of which a number of small tubes project downwards into a tank filled with cold water; and a cylinder and piston mounted on the top of the box. The mode of operation is as follows:
A roll of the prepared gutta-percha is introduced into the cylinder immediately above the die-box. The piston is then replaced, and forced steadily downwards by hand or other suitable power upon the gutta-percha, which, becoming softened at the lower end by contact with the hot die-box, escapes from the pressure through the tubes in a series of threads, which, as they drop into and are cooled in the water in the tank, and carried around a roller, whence they are conducted to and wound upon a set of revolving reels, after the manner of hand-spinning, that is, by working the thread between the fingers and thumb, the thread may be stretched about four times the original length. The threads are then wound off on bobbins and ready for use.