Since the top surface resists wear for so long the key to determine when a new strap may be required is to look at the underside. This area often shows the most wear due to this surface being in contact with the wearer skin, soaking up sweat and dirt from the wrist. Due to the porous nature of leather, it is not possible to remove these marks with any real success and the salts and acid contained in the sweat will eventually break down the leather. If the watchstrap has taken on a very dark color to the underside and also exhibits cracks when being manipulated, it is advisable to replace the strap before it breaks apart. A broken strap can result in the watch falling from the wrist, a potentially costly event.
Modern leather straps are beautifully made items that, if looked after, can retain their looks for some time. However, as an organic material the life expectancy of leather is limited by environmental factors and overtime sweat, along with wear and tear, will take their toll. In order to preserve the condition of a leather strap as long as possible and prevent discoloration and deformation it is advisable to steer clear of contact with sources of moisture. Prolonged exposure to sunlight should also be avoided to prevent color fade, Leather has a complex, permeable, structure and contact with solvents, detergents, perfumes and cosmetic products should be avoided as these can invade the leather, degrading it from within.
One of the advantages of leather is that as it ages it conforms and moulds perfectly to the shape of the wearer’s wrist, allowing a comfortable position for the watch. As with marks on the watchcase, a little visible wear is not always a bad thing, and the appearance of some leather are much improved with age.
There are many different types of leathers and the spectrum of leather cleaners is so broad that the cleaning of a leather strap is not advisable.