Towels become stiff primarily because free calcium and magnesium ions in the water combine with soap to form calcium and magnesium soaps that adhere to the towel's surface. To prevent this, besides frequent washing, towels should be boiled in an alkaline solution for 15 minutes (generally, 30 grams of baking soda are sufficient for 1.5 kg of water; ensure the towel is completely submerged). After boiling, remove the towel and rinse thoroughly with clean water.
Towels become oily and sticky because they accumulate a large amount of sweat, tears, and other secretions. To clean slippery towels, in addition to the above methods, you can boil or scald them in concentrated salt water.
Bacteria thrive best in high temperature and humidity, so towels should be kept dry. However, many bathrooms lack windows and have poor ventilation. To maintain cleanliness, towels should be washed with soap daily and then hung to dry in the sun or a well-ventilated area. They should also be boiled in salt water once a week. Microwaving towels after wetting them is also an effective method of sterilization.
