CHROME TANNAGE USING HIGH-INTENSITY ULTRASONIC-FIELD

The process time in chrome tannage in leather making, using an elastic compression cycle followed by irradiation by high-intensity ultrasoun d, is quite short lasting only a few minutes, compared with a process time of several hours in modern chrome tannage. After ultrasonic irrad iation, samples were basified in 17 h in chrome liquor at a pH of 4.0 and the shrinkage temperature was measured. The determination of the e fficiency for the chrome liquor penetrating into the hides can be base d on the steepness of the shrinkage temperature-processing time curve. An approximate value of 20 degrees C min(-1) can be evaluated for the initial slope of the curve when elastic compression and high-intensit y ultrasonic irradiation is used, and a processing time of 2 min is re quired in chrome liquor (plus 17 h basification and 24 h storage time) to obtain leather stable to boiling. Usually, hides are kept in chrom e liquor for 2 h. (C) 1997 Elsevier Science B.V.