160 



THE INDIA RUBBER WORLD 



[December 1, 1919. 



eting or trapping of air, by improper tighletiing of clamps and 

 other causes. 



Retreading materials should be especially compounded and 

 ordinary repair stocks should not be used. It is always well to 

 have the proper tools. A heavy tread roller is a good investment 

 and also a time-saver. A porcupine roller saves labor by rolling 

 out the air blisters. A few dollars spent on necessary and labor- 

 saving tools enable a man to turn out a first-class job. Neat- 

 ness, too, is a requisite. It is just as easy to turn out a neat job 

 as a slovenly one. Why not have a place for every tool and 

 wrench and have the clamps, bars and bags arranged neatly on 

 a shelf or rack? 



In a small shop visited in Canada the work was perfect in every 

 detail. The foreman said he seldom had two "touch ups" in a 

 week. The secret of his good work lay in the foundation of his 

 molds. These were polished after every cure with very fine 

 sandpaper or steel wool. A few hours devoted to the surface of 

 the molds, to cleaning them and keeping them clean, will prove 

 profitable. For this purpose, though solutions of various kinds 

 are used, plain Castile soap of the highest quality obtainable is 

 excellent. A light film of this, diluted in water, should be 

 painted on the molds: this will keep the rubber from sticking 

 to the molds, will do away with air pockets and will maintain 

 an even flow of rubber. 



SPLICING BALATA BELTING. 



BAi-AT.\ AND RVBBER differ radically in their nature and proper- 

 ties, which necessitates very different methods of treatment 

 in their manufacture. Balata belt making, previously described 

 in detail in The India Rubber World, May 1, 1919, does not 

 include vulcanization as in the case of rubber and this makes 

 the process of splicing balata belting a specifically different pro- 

 cess. The preparation of the ends requires the use of a square, 

 a knife, and a warming iron for softening the balata, to permit 

 separation of the plies, a special scraper for use on the balata 

 surface, and balata cement, a solution of balata in a volatile 

 solvent. 



The preparation of the belting for a sphce, in either rubber 

 or balata, involves removal of the duck plies of each end to be 



(R. &■ J. Dick, Limited.) 

 The Plies of E.^ch End 



joined in a series of steps spaced so that each end will replace 

 the removed portions of the opposite sides of the joint. 



The prepared surfaces having been warmed by radiation from 

 the red-hot iron heater held a short distance over them, are 

 brush coated with the balata solution. The surfaces are dried 



perfectly by about 30 minutes' exposure. The laps are heated 

 until they are very tacky, when they are carefully matched and 

 clamped together in a suitable bench belt press, which has been 

 well wetted to prevent the belt from sticking to it. The splice 

 remains under moderate pressure for about ten minutes. After 



!• -•: Moderate 



removal from the press the joint is cooled in water and 

 strengthened by sewing or riveting, or by diamond stitching with 

 rawhide. 



PILOT BALLOONS. 



ONE REMARKABLE new development brought on by the war has 

 been the scientific observation of the upper air, the measure- 

 ment of horizontal and vertical distance, the marking of air cur- 

 rents in which the departments of the Government have shared — 

 the War Department, the Navy and the Meteorological Section of 

 the Department of Agriculture. Very soon they found it possible 

 to work in harmony with each other and also with the air serv- 

 ices of Great Britain, France and Italy. 



Hundreds of young men were trained in the Signal Corps and 

 other branches to take the necessary observations and many ac- 

 companied the forces abroad. The Ordnance Department needed 

 the information because the knowledge of air conditions was es- 

 sential in the handling of guns; that knowledge was vital to the 

 men who went up in airplanes and dirigibles, whether fighting at 

 the front or carrying mails and despatches; it was needed 

 by the Navy for vessels and airships. 



Among- the instruments found useful were the little pilot bal- 

 loons made of rubber. They were used to determine altitude 

 conditions, air currents at different elevations and the velocity 

 of the winds, and, when the armistice was signed, were about to 

 be sent over enemy lands to distribute literature that might dis- 

 concert the foe. 



The balloons used had to admit of high inflation and to have as 

 little weight as possible. They were made of rubber, so cured 

 as to retain its elasticity for a while and to allow the hydrogen 

 to diffuse only slowly through its walls. Pure rubber balloons 

 of a spherical shape were used, either uncolored for use 

 against a clear sky or dark red for cloudy weather. The smaller 

 size inflated to a diameter of 80 centimeters, weighing 20 or 30 

 grams, the larger, of 120-centimeter diameter, weighed 50 to 60 

 grams. It was very difficult to manufacture satisfactory balloons 

 larger than 9 inches in diameter when uninfiated. 



The balloon ascends at a remarkably constant rate, about 10 

 feel a second. It is kept in sight up to distances as tar as 60 



