Rate of Deposition of Latex on Porous Molds

The effects of pressure, rubber concentration of latex, temperature, and hydrogen-ion concentration upon the rate of deposition of latex on porous molds are described. Pressure, rubber concentration, and temperature were found to be negligible factors in comparison with hydrogen-ion concentration. By adjusting the pH of the latex to 6.1 it was found possible to obtain aggregation of the latex particles and a marked increase in rate of deposition. THE manufacture of rubber articles by dipping porous forms in latex was first described by Condamine (5). He reported to the Paris Academy in 1736 that the natives in South America made such articles as shoes and bottles, using clay molds which, after drying of the deposited layer, were shattered and removed. The idea of making articles by a process of this sort, instead of by coagulating the latex, milling, and then shaping the milled rubber, appeals to the imagination. Increased tensile strength and improved aging have been claimed (10) for articles made directly from latex, and their remarkable resistance to tear, obtained under certain conditions, is well known.