720 



THE INDIA RUBBER WORLD 



JuLV I, 1921 



dipping tank during the intervals between dips, and also by addi- 

 tions of fresh standard cement, or even by stirring in small quan- 

 tities of solvent as required. 



An interval of about one hour between dips is observed in 

 making balloons and nipples, and double that in the case of 



Fig. 9. Drying Room 



gloves. This is requisite to permit air carried down by the 

 forms to rise to the surface, or gas from the solvent that may 

 be evolving from the cement. An interval between dips is also 

 needed so that each film of rubber may dry before the next is 

 added. The following table gives the number of dips and inter- 

 vening lapse of time for various goods : 



Dipping Table 



Number of Interval Between 

 Article Dip Coatings Dippings 



Tov balloons 3 tr 4 45 minutes 



Finger coto 6 to 7 2 hours 



Con^pounded gloves 4 2 hours 



Pure-gum gloves 9 2 to 2 "^j hours 



Nipples 10 to 12 1 hour 



DKYING 



Final drying follows the last dipping to eliminate all the 

 solvent before curing. If done under variable weather conditions, 

 the drying time will vary from eight to 24 hours. By far the 

 better method is to employ conditioned air as described in a pre- 

 ceding paragraph, because in that way the drying process can be 



Bai.loon-Finishing Department 



regularly scheduled with saving of time and certainty of pro- 

 duction. 



Dipped goods, like other rubber products, are made to standard 

 weights and standardization is regulated in the dipping room 

 by test-weighing samples stripped from forms as the dipping 

 nears completion. 



FINISHING ROOM 



Subsequent to dipping and drying, the goods are taken to the 

 finishing room where the work of forming beaded edges is done 



by rolling the rubber back upon itself, either by hand or ma- 

 chine, and in the case of gloves by applying strips o.f rubber as 

 reinforcement around the wrist. 



BEAD EOLLING 



A patented machine for rolling beads on dipped articles is 

 shown in Fig. 11. In this machine the dry uncured article on 

 its form is 

 made to pass 

 between two 

 yielding rolls of 

 sponge rubber, 

 both of which 

 revolve upward 

 against the edge 

 of rubber which 

 is to be beaded. 

 The form re- 

 volves as it 

 passes the roll- 

 ers. The latter 

 are inclined at 

 an angle with 

 relation to the 

 horizontal pas- 

 sage of the rub- 

 ber edge of the 

 article and for 

 that reason they 

 roll the edge of 

 the rubber up- 

 ward only to a definite height, thus forming a 

 of definite size. 



This machine, when equipped with brush rollers, can be used 

 for stripping small objects like balloons, finger-cots and nipples 

 from their forms after curing, and also for cleaning and polishing 

 forms. 



ACID CURE 



Vulcanization by the acid-cure is effected by immersion of the 

 dried dipped article on its form into a curing bath consisting of 

 sulphur chloride and carbon bisulphide. The ordinary propor- 

 tions are four liquid ounces of the former in five gallons of the 



Fig. 11. Hadfield's Bead-Rolling Machine 



rolled-up edge 



i<iG. 12. Balloon-Stripping Room 



latter. The time of immersion necessary for thorough cure 

 varies from IS to 60 seconds according to the thickness of the 

 rubber. In the case of nipples afteracid-curing on the outside 

 they are removed from the forms and curing acid is poured into 

 each to cure the inner surfaces. 



VAPOR CURE 



.. UlovcS are usually cured by exposure to the vapor of sulphur 

 chloride in an enclosed space at 180 degrees F. for an hour, more 



