Arizona republican., 1921-03-13
Rubber's Evolution
 Interesting Chapter

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 vuIcanization is a term frenquently used by motorists, to nearly everyone of whom it has a mental association with tire repair shops. Many believe it to be another name for tire repair. But vulcanization has not so limited a meaning as that. It is the process on which the whole rubber industry of the world rests. Every article of rubber manufacture that enters into the serv- ice of mankind has been vulcaniZed. Whether it is a teething ring or a tire, a hose pipe or a hot water bottle, a rubber boot or a golf ball, it must have passed through the process of vulcan ization.
 Rubber manufacturers did not al- ways know how to vulcanize rubber. Before the process was discovered mill lions of dollars were spent in this coun- try in the manufacture of rubber goods that reached the market only to prove unsatisfactory. Many factories were erected, especially in New England, but all were a loss.
 Daniel Webster in the famous law suit in which he defended the first vulcanization patents, said of these early efforts at manufacture:
 All these factories, all the earnings of the individuals connected with the business came to an end and nothing was done until business was revived by the invention of vulcaniZation."
 These efforts at manufacture failed because of the inability to remove sev- eral objectionable qualities in the rub Der itself. Among these were a ten dency to stiffen and harden and lose elasticity in cold weather. and to be- ome soft and decompose in warm
 eather. A rubber coat would become
 stiff in the winter that it would
 and of itself like tent. In the sum
 CT time rubber goods on the shelves T +s0l~. nd in time become shapeless mass of composing vegetable matter. Odors
 ere so highly offensive as to consti-
 lte a bar to successful sales.
 The discovery of the secret of con- erting rubber from this useless state ato one of the most serviceable sub stances known to man was one of the treat discoveries of the age. The in .entor Charles Goodyear learned the secret only after ten years of arduous toll.
 It is this process which constitutes what is known as vulcanization. First and several years prior to the full solu ion of the problem, it was learned that sulphur mixed with the crude rubber produced some changes for the better. But the complete elimination of the ob- iectionable features was effected a number of years later when the discov- cry was made that the mixture of sul- phur and rubber when exposed to a high degree of heat produced change" in the rubber that gave it those qualities of durability and per nanenee which have made it valuable n so many ways.
 Vulcanization increases the elasticity I'd distensibility of rubber and makes it insusceptible to changes of tempera- ture. In fact, when heated, the vul- canized rubber does not fuse and be- come clammy and viscid, but remains 1E the absolute decomposition point Oil and grease, which formerly softened it | so quickly as to make it unsuitable, no | longer do quick harm to 1t, although in some forms, especially tires, oil and grease are counted among the chief en- epies of long life for rubber.
 l VulcaniZation is generally spoken of among rubber manufacturers as the cure" Many efforts have been made | to discover other and less expensive methods of curing rubber but thus far without much success. In every rubber factory a large part of the cost of ma chinery and of labor is applied to se- curing a proper cure. True, some types of thin goods have been successfully vulcanized by the use of chemicals in place of heat but the proportion of these is very small.
 In tire manufacture vulcanization is especially expensive This operates in two ways, first, in the cost of the oper- ation itself, and, second, in the cost of adequatc supervision to make sure that materials are got spoiled during the process. To illustrate the necessity of this supervision it is necessary only to point out that a single drop of moisture in the rubber or fabric will. when the tire is subjected to heat in the vulcan- izer, turn to stean- and expand into a blister that will ruin the tires sale ability.
 4I,x z the equipment are the big tanks" in which the tires get their heat bath After the tire is built it is placed in a steel mould weighting from 500 to 5000 pounds. Putting the tires into these moulds and taking the out again and transporting the moulds about the factory requires an amount of labor that is an important item in the cost of a tire.
 When the building of a tire has been completed and it has been placed in the mould. it goes into the vulcan izer-a big hollow tank capable of hold ing a dozen or more tires of average size. When the tires are in place in the vulcanizer, the lid is screwed down and the steam turned in. The tem- perature rises gradually for 20 minutes when temperature of about 2S6 de- grees is reached. The tire remains at this temperature for about two hours, when the steam is turned off. After 15 minutes of cooling the moulds are taken out and the tires removed, and stripped from the cores on which they were built.
 Once a tire has been vuICauized it cannot be changed It is like a jar in a pottery until it is baked anything can be done with it, but once naked irs form becomes permanent and changes cannot be made. The task of regulat- ing the degree of "cure" is a matter for the expert. It took the inventor Of vul- canization six years after he had dis covered the right theory to reach by endless experimentation the point ] where he could give the rubber just the cure that was needed