August 1, 1916; 



THI INDIA RUBBER WORLD 



Rubber Cements in Leather Goods Manufacture. 



ONP: ..t the most valuable uses of rubber, and also a most 

 widespread one, is as an adhesive. As sucli. it is a 

 necessity in many trades. Rubber cements are many and 

 varied, differing in properties and qualities according to the re- 

 iiuircments of the various uses. 



In niannfattuiies of leather, good ruliber cements are especially 

 \ahiaMe. Wlhile many leather articles are made liy stitching the 

 dilfcrent parts together, others, particularly those of lighter 

 Uath'er, are fasrened wliolly l)y cementing, or by cementing and 

 then reinforcing by stitching. Rubber cements figure in many 

 trades. Bag and pocket-book makers, hatters, 1)ox makers and 

 shoe manufacturers lise large quantities. These cements are 

 used today for purposes which years ago were undreamed of. 

 Some of them have a tenacity sufficient to be used in processes 

 where formerly tacks were employed. This is the case with 

 sole-laying cement, used in .shoemaking, to hold the sole in place 

 to the lasted upper, preliminary to stitching. 



.\n(! in many other processes of shoe manufacture cements arc 

 used, their composition varying to adapt them to the special 

 work they are required to perform. 



In trade parlance, cements made of gutta percha are included 

 under the generic name of rubber cements, though the purist 

 might pronounce such a misnomer. As a rule, cements are 

 mainly solutions of gums in naphtha. There are other solvents : 

 chloroform, ether, bisulphide of carbon are efficient for this pur- 

 pose, but are too e.xpensive for general use. For some degrees 

 of tenacity gum mastic, gumlac, or ordinary rosin is added. 

 Such cements require heating and softening to apply, but these 

 ingredients add brittleness, a cpiality which unfits cements con- 

 taining them for juining where suppleness is retiuired. 



SOLE-LAYING CEMENT. 



To make a cement for sole laying, the following formula is 



recommended : Lagos buttons or strips, 10 pounds ; Pontianak, 



,^ pounds; naphtha. 20 gallons. This is also used as an oil proof. 



CII.\NNET. CEMENTS. 



Chainiel cement.-, are used to close the lip of leather uliich 

 lias been raised to allow the sole to be stitched to the welt, the 

 object being to cover the stitches and give a smooth, unbroken 

 linish. For such cement various formulas are presented. For 

 these, the rubber used is washed but not sheeted. Three of 

 ihese are similar, but the ipiantity of rubber varies. Each con- 

 tains 5 pounds of rosin and 40 gallons of naphtha, but one calls 

 for 10 pounds, the second for _'0 |iounds and the tliird for 30 

 pounds of Para ruliher. 



.■\ fourth channel cement calls lor 10 pounds of Madagascar 

 pinky, 40 ounces of rosin and 20 gallons of naphtha. 



Xumber .S requires 12 pounds of Madagascar rubber. 12 pounds 

 of Madagascar niggers. 8 pounds of rosin, 2 pounds of coninion 

 liilcli and 50 gallons of nai)htha. 



.\nother channel cement receiiit is 6 pounds of line I'arn rub- 

 ber. 4 pounds of hard .\frican rubber, 16 gallons of narihtha, 

 and of rosin, 3 (mpuuiIs in the summer or 2 |)ounds in winter. 

 tor.ORED CEMENTS. 



If colored cements are desired, most formulas are practically 

 the same as the first three channel cements mentioned above, 

 with aniline dyes in proper proportions. For instance, a batch 

 of 40 gallons, to be colored black would require Y- ounce of 

 black aniline. For red cement, Vs ounce of red aniline is needed 

 to each 40 gallons. Blue cement would require 2 ounces of blue 

 aniline. Green cement should have 2 ounces of green aniline. 

 Yellow cement needs 3 ounces of yellow aniline to acquire the 

 proper color .Another black cement is made of Para rubber. 



20 pounds; rosin. ,S pomuls ; bone black, 5 ounces: and naphtha, 

 40 gallons. 



WELTING CEMENT. 



I'or welling cement 10 pounds fine Para rubber (sheeted) and 

 5 ounces of sidphur, are mi.Ned and dissolved in 10 gallons of 

 naphtha. A somewhat similar paste cement is 10 pounds of 

 Maiunga rubber (sheeted) and 20 gallons of naphtha. Where 

 it is necessary that the cement shall not stain, as in cementing 

 shoes of white leather to canvas, a paste cement is made of 

 East Indian pale crepe, 20 pounds, to 50 gallons of naphtha. 

 FOR SHOE REP.MR. 



Shoe repairers use cements to patch leather shoes. By skiving 

 the patch d'uvn ti' a thin edge, and cementing, a much neater 

 job is done than in the now almost obsolete way of stitching 

 the patch on. For such purpose either one of the channel 

 cements or welting cements mentioned above are suitable. 

 UrP.IUCR HEEL CEMENTIXC. 



For attaching rnbber heels and soles a special cement is re- 

 commended, which is made as follows: gutta percha (lincly cut), 

 20 parts: ammonium sulphide, 18 parts; benzol, 3 parts; and 

 turpentine. 24 parts. This combina,t|i^n is dissolved by shaking 

 in a container at a slightly warm terripcrature, after which 35 

 parts of finely powdered asphalt are added, and the closed con- 

 tainer thoroughly shaken for several days. This cement, which 

 has a syrupy consistency, is warmed by immersion of the con- 

 tainer in boiling water, and applied to the leather surface, 

 properly prepared for it; then the sole or heel is laid on and 

 subjected to a heavy pressure. A second cement for this purpose, 

 which dries more quickly than the above, is made in two solutions, 

 equal parts of each I'cing mixed together at the time of apply- 

 ing. One solution contains 20 parts of finely cut gutta percha 

 and SO parts of ammonium sulphide. The second solution is 

 20 parts of shellac. 2 parts of crude turpentine, and 70 parts 

 of alcohol. 



l'l;i;( Al'IKlX.S .M-.CKSSAk\'. 



Leather and ru!)l'cr surfaces, to which rnbber cements are to 

 l:e applied, need special preparation to secure successful ad- 

 hesion. Both should be roughened, — the leather, to produce a 

 fibrous surface for the penetration of the cement ; and the rub- 

 ber, for the removal of any incrustation of sulphur or talc. If 

 the leather is at all oily a washing of the buffed surface with 

 benzol is recommended. 



For use on leather which contains oil, a cement is manufac- 

 tured which contains a percentage of talc, powdered soap-stone. 

 whiting, or some similar substance. This absorbs the oil, and 

 allow; the cement to perform its function. The.se substances 

 r|.. n.u di^■.olve, l)Ut are held in suspension in the cement, which 

 innsi l.c tlioroiighly agitated before applying. Such cement is 

 parti' ularl) u-cful in turning in the skived edges of shoe up- 

 pers, :o produce a smooth finish. 



P.XTCITINC; UUBIiER SHOES. 



Shoe repairers are often called upon to patch rubl)er footwear. 

 .\ cement made for this purpose is made of Para rubber. 20 

 pounds: rosin, S pounds, and turpentine, 80 pounds. 



rchheu nr..\CKiNGs. 



Two receipts f.ir rnbber blacking may be apjiropriatsly given 

 in this connection. .\ rubber blacking formula recommended is: 

 caoutchouc oil. 12 pounds; acetic acid, 12 pounds: vinegar, 12 

 pounds ; molasses. 20 pounds ; and lamp black, 44 pounds. 



.\ liquid blacking contains caoutchouc oil, 4'/2 pounds ; sul- 

 phuric acid, 12^ pounds ; vinegar, 27 pounds ; gum arable solu- 

 tion, '/■• pound : molasses, 2V/: pounds ; bone black, 32 pounds. 



