Guideline for Selecting Starch Paper for the Iodine-Paper Technique to Assess Active Sweat Glands on the Skin in Active or Passive Heating Environments

The paper provides recommendations and a practical approach for selecting starch papers for the iodine-paper technique, a method used to measure the number of active sweat glands in the skin in active or passive heating environments. Twelve types of papers were selected for the present study. All the papers were dehumidified and saturated with iodine 6–30 h. A subject participated in the heat stress test (20-min exercise) and active sweat glands were measured on the hand and finger. Papers numbered 1, 2, 4, and 5 showed the best results, which varied according to the saturation time with iodine (6 h for sample 4, 24 h for sample 5, and 30 h for samples 1 and 2). The minimum absorbed time for all samples was 6 h. The surface properties of the paper were crucial for clear imprinting. Active sweat glands were observed on smoother paper without visible surface fibers and bumps, which hindered the accurate counting of sweat glands. The imprint quality did not depend on the paper thickness, weight, density, or hydrophilic properties. On the other hand, the changes in iodine saturation time and storage conditions affected the imprint quality. In addition, when measuring the sweat gland imprint, they were more distinct during the daytime (morning and afternoon) and fibers should be selected. In addition, one skilled experimenter should conduct the than in the evening. In conclusion, white starch papers with smooth surfaces with no bumps measuring procedure to avoid deviations in pressure at an identical time.