334 



THE INDIA RUBBER WORLD 



lAi'RiL 1, 1916. 



GROUP 1 

 1. Bourn's Ammonia Method. — By the evaporation of ammo- 

 nium carbonate in a vulcanizing chamber adapted to retain 

 pressure, an atmosphere is secured in which boots and shoes 

 are cured in about thrce-(iuarters of an hour. The vulcaniz- 

 ing heat is derived from steam circulating in a jacketed space 

 surrounding the curing table. 



2. Bourn's Co.mpressed Air Method. — Compressed air in the 

 curing chamber is employed to solidify the goods and to 

 hasten vulcanization by its increased conductivity. Heat is 

 supplied by steam circulating in a surrounding jacket. 



3. DuNC.\N TousLEV Method. — The goods, upon lasts, are 

 sealed against the contact of air or steam. With this protection 

 they are placed in a vulcanizing chamber which is hermitically 

 closed. Air, heated to 280 degrees F., is introduced until the 

 pressure reaches 60 pounds. The air is retained in the cham- 

 ber about 45 minutes, until the goods attain approximately 

 270 degrees F. The air supply is then cut off and the confined 

 air displaced by steam at about 80 pounds pressure. Vulcani- 

 zation takes place in dry steam. At the completion of the 

 process the steam is displaced by air to cool the goods before 

 opening the vulcanizer. 



4. Hill's Method. — The goods, upon lasts, are vulcanized in 

 an atmosphere of dry carbon dioxide maintained at any desired 

 pressure up to 100 pounds per square inch. The walls of the 

 vulcanizing chamber are heated by a steam jacket, and the 

 interior of the vulcanizer by a steam coil. 



5. Cockburn's Method. — .An ordinary single or doulile-jacketed 

 vulcanizer is employed in which the goods, on lasts, are 

 placed and heated by dry steam in an atmosphere of com- 

 pressed air. 



6. Rutherford's iMf.thod. — The goods are made upon speci.il 

 lasts provided with ducts lor the withdrawal of moisture from 

 the shoes, and adapted for connection as part of a tubular 

 frame car attachable to an air pump inlet in the shell of the 

 vulcanizer. Thus connected the moisture can be withdrawn 

 from the goods and vulcanization effected subject to the 

 action of a controllable pressure. 



GROUP 2 



1. Warner's Method. — The goods, on lasts are placed in a vul- 

 canizer which has been previously heated. By means of a 

 vacuum, all the confined air and volatile gases are removed 

 from the heated goods, after which a constant pressure of 

 pre-heated air or inert gas replaces the vacuum during the 

 period of vulcanization, and the required temperature is main- 

 tained until completion of the cure. 



2 Crowley's Methi.d. — The goods are built on lasts adapted 

 tor attachment to a device for removing the trapped air or 

 moisture. The goods may then be vulcanized by any suitable 

 means, using hot air or gases with or without pressure. 



3. Hill's Method. — One of the objects of this process is the 

 exclusion of the air from contact with the rubber during 

 \ ulcanization. to avoid oxidation. To attain this, a thin, 

 steam-tight, ruliber-and-fabric envelope is provided to fit 

 o\ er the shoe and from this the air is removed, causing it to 

 conform snugly to the contour of the shoe. It is then tightly 

 .sealed in that position. With each boot or shoe thus pre- 

 pared, the goods are cured in an atmosphere of steam. 



4. Price's Method. — The shoe or boot is built up on a special 

 last or boot tree with perforated walls and mounted so that 

 the interior and exterior pressure conditions can be con- 

 trolled, the interior pressure being less than the exterior 

 pressure either before or during vulcanization, or both. By 

 this means, air is removed from the materials and the struc- 

 ture of the goods. Hot air, hot gases or other means may 

 be employed as the vulcanizing medium. The method also 

 provides for pressure control in connection with the heating 

 medium during vulcanization. 



GROUP 3 



— .\ speci; 



uid serves as 



Pressure Cure Vulcanizer Receiving .\ Car of Boots. 



steam-heated mold. Against the interior of this mold the 

 shoe is compressed by air to solidify the plies of material. 

 2. Field's Method. — The goods are compressed on metallic 



