A method of drying a medical instrument in a vacuum chamber, comprising (a) initiating a timer in a digital computer; (b) withdrawing a first volume of air from the chamber; (c) repeatedly determining pressure within the chamber while withdrawing the first volume of air from the chamber; (d) calculating, with the digital computer, a first, second and subsequent second-derivative values to obtain a first group of second-derivative values of pressure with respect to time; (e) calculating, with the digital computer, a first summation of positive differences between consecutive second derivative values from the first group of second-derivative values; (f) comparing the summation to a threshold value, the summation indicating that residual moisture is or might be disposed upon the instrument when the summation is greater than the threshold value and indicating that the instrument is dry when the summation is less than the threshold value; either: (g) determining that the summation is greater than the threshold value; (h) opening a valve to introduce a second volume of air into the chamber; (i) withdrawing the second volume of air from the chamber; (j) repeatedly determining pressure within the chamber while withdrawing the second volume of air from the chamber; (k) calculating, with the digital computer, a second group of second-derivative values of pressure with respect to time; (l) calculating, with the digital computer, a second summation of positive differences between consecutive second derivative values from the second group of second-derivative values; (m) repeating step (f); or (n) determining that the summation is less than the threshold value; (o) opening the valve to introduce a third volume of air into the chamber; and (p) opening the chamber; or (q) stopping the drying method if the digital computer times out. (a) initiating a timer in a digital computer; (b) withdrawing a first volume of air from the chamber; (c) repeatedly determining pressure within the chamber while withdrawing the first volume of air from the chamber; (d) calculating, with the digital computer, a first, second and subsequent second-derivative values to obtain a first group of second-derivative values of pressure with respect to time; (e) calculating, with the digital computer, a first summation of positive differences between consecutive second derivative values from the first group of second-derivative values; (f) comparing the summation to a threshold value, the summation indicating that residual moisture is or might be disposed upon the instrument when the summation is greater than the threshold value and indicating that the instrument is dry when the summation is less than the threshold value; either: (g) determining that the summation is greater than the threshold value; (h) opening a valve to introduce a second volume of air into the chamber; (i) withdrawing the second volume of air from the chamber; (j) repeatedly determining pressure within the chamber while withdrawing the second volume of air from the chamber; (k) calculating, with the digital computer, a second group of second-derivative values of pressure with respect to time; (l) calculating, with the digital computer, a second summation of positive differences between consecutive second derivative values from the second group of second-derivative values; (m) repeating step (f); or (n) determining that the summation is less than the threshold value; (o) opening the valve to introduce a third volume of air into the chamber; and (p) opening the chamber; or (q) stopping the drying method if the digital computer times out. (g) determining that the summation is greater than the threshold value; (h) opening a valve to introduce a second volume of air into the chamber; (i) withdrawing the second volume of air from the chamber; (j) repeatedly determining pressure within the chamber while withdrawing the second volume of air from the chamber; (k) calculating, with the digital computer, a second group of second-derivative values of pressure with respect to time; (l) calculating, with the digital computer, a second summation of positive differences between consecutive second derivative values from the second group of second-derivative values; (m) repeating step (f); or (g) determining that the summation is greater than the threshold value; (h) opening a valve to introduce a second volume of air into the chamber; (i) withdrawing the second volume of air from the chamber; (j) repeatedly determining pressure within the chamber while withdrawing the second volume of air from the chamber; (k) calculating, with the digital computer, a second group of second-derivative values of pressure with respect to time; (l) calculating, with the digital computer, a second summation of positive differences between consecutive second derivative values from the second group of second-derivative values; (m) repeating step (f); or (n) determining that the summation is less than the threshold value; (o) opening the valve to introduce a third volume of air into the chamber; and (p) opening the chamber; or (n) determining that the summation is less than the threshold value; (o) opening the valve to introduce a third volume of air into the chamber; and (p) opening the chamber; or (q) stopping the drying method if the digital computer times out.