122 



THE INDIA RUBBER WORLD 



[January i, 1905. 



SOME POINTS ON SHEET PACKINGS. 



BY I. \V. C. 



IN cleaning up a rubber shop at inventory time, or other oc- 

 casions more or less perfunctory, it is not an uncommon 

 experience to round-up a lot of odds and ends in the form of 

 " experimental " compounds, and surplus from completed or- 

 ders, of varying costs and utility, and not infrequently repre- 

 senting a considerable money value. The best of it can be held 

 against possible future orders, but the balance is of concern to 

 the superintendent, for it surely ought to be utilized, and con- 

 sequently, is consigned to that factory terra incognita, the 

 " friction," or is worked up into cheap packing. 



No doubt cheap packing has come to stay, in a sense, but it 

 is unfortunate that, in the desire, and perhaps necessity to meet 

 competition, it should frequently be necessary to use materials 

 that to a degree represent a gamble with chance. 



This desire to utilize all material that otherwise would be con- 

 signed to scrap, is much in evidence in factories where bicycle 

 tires are made in quantity. Here trimmings of frictioned duck 

 and muslins would accumulate, were they not successfully util- 

 ized in the manufacture of packings requiring a compact body 

 or base. For this purpose the frictioned material is built into 

 great slabs to a designated thickness and then cut into strips 

 and reinforced on one or both sides by a layer of compounded 

 stock. One enterprising superintendent, being unable to find 

 a market for all this sort of packing, utilized the " friction " in 

 the extensive manufacture of cement — " but that is another 

 story." 



Packing has a variety of functions : as applied to piston rods ; 

 to render a joint steam tight as in a manhole or handhole, and 

 in pumps and pipe lines. The importance in sheet packings in 

 the rubber manufacturing industry is evidenced by the large 

 number of brands, each manufacturer apparently being ambi- 

 tious to convince his customers that he alone has " the real 

 thing." 



The result is seen in innumerable fetching titles, and the em- 

 ployment of difTerent colors. It is open to question, however, 

 whether the particular color has any great significance in so 

 far as quality is concerned, as the permanent popularity of any 

 packing lies in the power of the compound of which it is com- 

 posed to meet the requirements of its particular use. Thus a 

 very cheap material, reinforced by plies of muslin or duck, as 

 seen in the ordinary C. I. sheet, will answer every reasonable 

 demand when used in low pressure steam lines or cold water 

 joints. But even in this situation complete satisfaction is 

 doubtful if joints are frequently broken, as it has no lasting 

 qualities. 



It follows, therefore, that for steam lines, or locations subject 

 to high temperatures, quality and adaptation must be consid- 

 ered. Expansion and contraction are to be reckoned with ; 

 hence the packing that retains its elasticity the longest, al- 

 though the more expensive, will prove the more satisfactory. 

 With few or no exceptions there is no vulcanized sheet pack- 

 ing made that will not in time harden when subjected to con- 

 tinuous steam heat. The term " vulcanized " does not imply a 

 cured packing. In fact, a sheet packing for steam joints, at its 

 best is semi-vulcanized. It should be so compounded and 

 cured as to retain its life, for unless it expands when subjected 

 to heat, its value is questionable. 



The experienced engineer, therefore, tests a packing before 

 using it by holding a piece in the flame of a match. If it swells 

 he may feel assured that it possesses at least one valuable qual- 

 ity. He will also see that all iron surfaces to be covered by 

 the packing are perfectly clean, that the packing is cut to a 



perfect fit. When the packing is in form of a molded C. I. 

 gasket that the splice is perfectly made ; that the bolt holes 

 " justify " exactly with the bolt holes of the joint or head. He 

 will then screw up the bolts when cold, and turn on steam 

 slowly. 



These points, though small, perhaps, should be well consid- 

 ered, for live steam is a most insidious thing, and will find a 

 defect if one exists. 



The thickness of a pure gum or C. I. packing in a joint is im- 

 portant. It does not follow because a joint has large circum- 

 ference that packing should be thick. The greater the surface 

 presented to the steam, the more pronounced the action of the 

 heat. When a packing becomes hard the greater is its liability 

 to crack and blow out. It will be found, therefore, where the 

 surfaces to be packed are perfectly smooth, that a packing up 

 to Tj '"ch in thickness will meet all requirements. On the 

 other hand, for a rough joint, use y'-i inch, that there may be 

 sufficient packing to fill all inequalities of surface and still 

 make the joint perfect. 



LITERATURE OF INDIA-RUBBER. 



CELLULOSE, CELLULOSE PRODUCTS, AND ARTIFICIAL RUBBER 

 Comprising the Preparation of Cellulose from Wood and Straw ; Manufacture 

 of Parchment: Methods of Obtaining Sugar and Alcohol, and Oxalic Acid; 

 Production of Viscose and Viscoid, Nitro-Celluloses, and Cellulose Esters, 

 Artiticial Silk, Celluloid, Rubber Substitutes, Oil Rubber, and Factis. By Dr. 

 Joseph Bersch. Authorized translation from the German, by William T. 

 Rrannt. Philadelphia; Henry Carey Baird & Co, 1904. [Cloth. Svo. Pp. 

 xxi +345- Price, 53.; 



THIS book is noticed here because of the inclusion of the 

 word " Rubber " in its title, and the high character of 

 the house publishing it, rather than on account of any practical 

 value it may have to the rubber industry. With respect to 

 cellulose products it appears very full and practical, but the 

 subject matter is for the most part foreign to the needs of 

 American rubber manufacturers, whatever may be true in 

 Europe. The 23 pages devoted to " rubber compounds " and 

 " rubber substitutes." may, however, be read with interest by 

 rubber men. 



INSULATING MATERIALS IN HIGH TENSION CABLES. BY E. JONA, 

 Chief Electrician of the tirm Pirelli & Co. Milan : 1004. [Paper, ismo. 

 Pp. 45 ] 



A PAPER read before the International Electrical Congress 

 at St. Louis in September last, and reprinted here in English 

 and Italian. A summary appeared in the issue of this Journal 

 for November i. 



THE COLORADO RUBBER PLANT. BY O. J. KENNEDY, SECRETARY 

 Salida Board of Trade, Salida, Colorado: 1904. [P.imphiet, Svo, Pp. 16. 

 Price, 25 cent>.] 



A HISTORY of the discovery of the plant; information as to 

 its culture, growth, and profits. 



IN CURRENT PERIODICALS. 



Plantations de Gutta-percha aux Indes Neeilandaises leurs Result- 

 ats. By Dr. P. van Romburgh. [Reprint of a recent official report.] 

 Revue des Cultures Coloniales, Paris, XIII-132, 133 (September 5, 20, 

 1903). Pp. 137-142; 168-173- 



ijber die netie Gtittapercha von Neuguinea \_Palaiiuium Supjianu7ii\, 

 By R. Schlechter=Z),fr Tiopenpflanzer, Berlin. VII — 10 (October, 

 1903). Pp. 469-471- 



Multiplication des Isonandra {Palaqiiiuiit gulla). By Charles Ri- 

 v\ire.=Jawfia/ d^ Agriculture Tropicalc, Paris. Ill — 28 (October 31, 

 1903). Pp. 291-293. 



Gutta perchas from the Straits Settlements. [Analyses and reports 

 on value ; extraction of Gutta percha from the \ea.ves.'\ = Bulletin of the 

 Imperial Institute, V.oaion. II-I (March 31, 19O4) Pp. 14-21. 



Le Marche de Caoutchouc de Bordeaux- [From Quinzaine Coleniale, 

 March iQi\. —Revue des Cultures Coloniales, Paris. XIV-146 (April 5, 

 1904). Pp. 202-203. 



