One of the important steps in the making of leather is the process known as bating or puering. This operation consists in treating the limed, unhaired skins with materials containing a proteolytic enzyme absorbed on an inert material, plus a deliming salt such as ammonium sulfate. The object of the process is to reduce some of the alkalinity of the skin and remove, from the grain surface particularly, any substance which would interfere with subsequent tanning operations.
Two of the properties of skin collagen which are of fundamental interest to the biochemist, and of practical concern the tanner, are the water-holding power of the protein, and the shrinkage temperature phenomenon. It was felt that the most worthwhile results could best be obtained by employing the most modern instrumental methods. In consequence a large part of the work was devoted to the development of electronic instrumentation, to aid in obtaining the desired information. The versatile high frequency oscillator titrimeter was adapted for the dielectric constant work on the water relationships of collagen, and an electrical strain gauge, and associated high-gain electronic amplifier, was developed to study the force shrinkage behavior of the collagen.