ハウツーキープHOW TO make leather last longer
Even if you take good care of your leather, water stains and mildew can be caused by carelessness. We asked a leather cleaning specialist about such leather problems, We asked a leather cleaning expert how to deal with such problems and what it means to wash leather products.
From "Leather in Japan No. 1," published in 2008
Q. Is leather prone to mold?
Leather, which contains moderate moisture and fat in its fibers, is a perfect condition for mold growth. Mold can easily grow on leather if it is careless. Particularly troublesome is mold that has penetrated into the leather's tissue, and when this happens, you have no choice but to give up. Leather goods should always be placed in a well-ventilated area. Also, once a shoe box is moldy, it should not be reused.
If the mold is only on the surface, it can be removed to some extent by wiping it off with a wet, tightly wrung cloth and drying in the shade.
Q. Is leather susceptible to rain?
A. Leather is inherently fibrous, and therefore, it is very susceptible to water. Some leathers are resistant to water depending on the dyeing or finishing method, but basically, leather can be considered weak against water. When it contains water, the leather's structure changes, which leaves marks. When heat is applied to it, it can even shrink stiffly. Therefore, if a drop of water gets on the leather, you want to immediately wipe it off by tapping it.
Experiment with an iron!
Moist leather is sensitive to heat. If you try to dry it suddenly with an iron, etc., it will shrink and become hard.
Q. Will water stains and mildew marks return to normal?
Stains and water spots inevitably appear as you use the product. And mildew that has grown without you noticing it. These can be refreshed by hiring a leather cleaner. They use a special detergent to wash the leather and dry it carefully before repairing it. Since it is quite difficult to wash in the same way at home, it is wise to leave the washing of leather goods to a contractor.
The photo shows the shoe cleaning procedure. Before soaking the shoes in detergent, dirt stuck to the soles is scrubbed with a stiff brush to lift it out.
Wash with a special water-soluble detergent. Apply a jet stream to the shoes soaked in the detergent bath to remove the dirt. Wash a total of five times, changing the detergent solution.
After rinsing with ozone water, let the shoes air dry naturally for at least 24 hours. Special keepers are inserted to prevent them from losing their shape.
Areas where the color has faded or water spots have formed are colored with pigment toned to match the original color.
The color-matched pigments are sprayed on using a spray gun. The process of reproducing the original color and applying the paint naturally is the work of a craftsman.
Before (right) and after (left) cleaning. Not only have the stains been removed, but the coloring has also made the areas where the color has changed due to fading from the sun or water stains almost invisible and natural.
Q. How do I properly store leather?
The general rule for storing leather goods, whether shoes, bags, or clothing, is to keep them in a well-ventilated place as much as possible. Also, the hot and humid climate in Japan is bad for leather, so it is best to keep it in an environment with low temperature and humidity if possible. If stored in a closet or closet, it is best to put it in the middle where air does not stagnate, and to take it out once a month to dry in the shade.
Avoiding high temperatures and humidity and ensuring ventilation is the basic principle for storing leather goods. Tokyo Wholesale offers a service where you can store your coats and boots in a storage room with a temperature of 10-15 degrees Celsius and a humidity of 55% during the spring and fall seasons for an additional 500 yen to the cleaning fee.
Q. Does leather stretch easily?
Leather stretches very differently depending on the type of animal, age, sex, part of the body and the direction in which it is taken. In general, the belly stretches more easily than the back, and the same back stretches better in the direction orthogonal to it than in the dorsal (backline) direction. Therefore, leather products are molded in consideration of the optimal position and direction for that product. However, it should be noted that leather products may stretch if they are stored in an unreasonable condition.
Tensile Strength and Elongation] We conducted an experiment to artificially pull a piece of leather. The test pieces were taken from pigskin in different parts and directions for comparison, but all eventually broke when pulled with great force. The belly was softer than the back in part, and the same back showed that the vertical specimen stretched longer before snapping than the dorsal specimen.
Q. Is leather heat resistant?
Leather has a property of hardening or deforming when exposed to heat above its heat-resistant temperature, and once deformed, it cannot be restored to its original shape. The heat resistance temperature at which leather does not deform is said to be around 120℃ in a dry state. However, this temperature varies greatly depending on the moisture content of the leather, and this temperature decreases when the leather gets wet. The temperature drops when the leather is wetted with water. Depending on the tanning method, the leather shrinks drastically at temperatures between 60 and 100℃.
Ironing test: A test piece is rubbed with an iron at 120℃, 160℃, and 240℃ from the left. The higher the temperature, the more the area where the iron was applied became wavy. This area was deformed because the leather was stretched and hardened compared to the surrounding areas. It cannot be restored to its original shape.
Q. Does leather fade?
There are several methods of coloring leather, including dyeing in a water bath, spraying or painting with a brush, and printing. The degree of color fading varies depending on the type of dye and finish, but as a general trend, leather with no surface treatment, raised leather, and leather with a leather-like finish tend to fade easily due to friction and other factors. In addition, it is important to note that color fading often becomes more severe when the leather is wet with water.
Dyeing and rubbing hardness: A white cotton cloth is placed over the rubbing element and rubbed on the surface of the leather specimen. The white cloth can be dry, soaked in distilled water, acidic sweat solution, or alkaline sweat solution. The pigmented leather did not fade much, but the unrefined leather faded with perspiration.
Q. Is leather damaged by sunlight?
All materials deteriorate under sunlight, but leather in particular shows changes in color. It depends on the tanning method, coloring method, dye and its concentration. In general, tanned leather is more susceptible to change and tends to turn brown than chromium-tanned leather. In terms of colorants, dyes are more likely to change color than pigments. In particular, light-colored leather tends to fade more noticeably than dark-colored leather.
Light resistance test: A piece of leather is tested by placing it in a light resistance tester that can accelerate exposure to sunlight. The photo on the right shows the results of exposure to light under certain conditions. The white ones turned yellowish. On the other hand, dark black did not show much change.
Q. Is leather still vulnerable to water?
When leather gets wet, water soaks into it, and when it dries, it may become stained or the surface may become uneven like a blister. For this reason, some leathers are finished with lacquer or urethane to prevent water from penetrating the surface. For leather without such a protective coating, try not to get it wet, and if it does get wet, immediately wipe it off by tapping it with a cloth.
Water droplet test: The surface condition of the test piece was observed after 30 minutes and 16 hours after it was wiped off. The brown leather piece showed no marks even after 16 hours. The black leather piece, on the other hand, was dark in color and showed almost no color change, but blister-like water spots were clearly visible after 16 hours. This difference is related to the surface treatment of the leather and other factors.
