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United States Department of Agriculture

Agricultural Research Service

Title: Area Retention Studies for Vacuum-Dried Leather

Authors
item Liu, Cheng Kung
item Latona, Nicholas
item Dimaio, Gary

Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 25, 2002
Publication Date: October 1, 2002
Citation: LIU, C., LATONA, N.P., DIMAIO, G.L. AREA RETENTION STUDIES FOR VACUUM-DRIED LEATHER. JOURNAL OF AMERICAN LEATHER CHEMISTS ASSOCIATION. 2002. V. 97. P. 355-368.

Interpretive Summary: Area yield is a very important concern for the leather producer because the price of a piece of leather is determined by its area. We took an integral approach and conducted a systematic study focusing on four factors simultaneously: initial water content, the concentration of fatliquor (lubricant and softening agent), drying time and the number of staking passes (mechanical pounding). We used a statistical program to formulate their interactive relationship on the area retention of leather. Observation showed that the area retention increases steadily with increasing either initial water content or fatliquor concentration. This trend slowly reverses, however, as both of these factors increase further. The effect of staking on area retention is also very intricate. Without the proper amount of fatliquor or initial water content, staking can significantly reduce area retention. This investigation gave a very systematic account of the effects of four variables and more importantly their interactions on area retention. To overlook or miscalculate on any one of these variables will have a significant impact on the area yield and consequently the tanner's profits.

Technical Abstract: The price of a piece of chrome-tanned leather is determined by its area. The importance of knowing the effect of leather making conditions on the resultant area yield cannot be over-emphasized enough. Shrinkage, however, is the most recognized phenomenon in the leather drying process. In our previous vacuum drying studies, we demonstrated that the residual water content is the key factor governing area retention. However, this general doctrine can be complicated by additional variables such as initial water content and the number of staking passes, particularly for toggled-dried leather because of the mechanical stretch that occurred. We, therefore, have conducted a systematic study focusing on four factors simultaneously: initial water content, fatliquor concentration, drying time and the number of staking. We used the SAS statistical program to formulate their interactive relationship on the area retention of leather. A second order polynomial regression equation was derived to plot 3-D response surfaces that clearly illustrate the relationship between the variables and area retention. Observation showed that the area retention increases steadily with increasing either initial water content or fatliquor concentration. This trend slowly reverses, however, as both of these factors increase. The effect of staking on area retention is also very intricate. Without the proper amount of fatliquor or initial water content, staking can significantly reduce area retention. This investigation has attained comprehensive information of the effects of these four variables and more importantly their interactions on area retention.

Last Modified: 12/19/2014
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