Discussing DLC:

Milling literally cuts steel into the right shape, versus having to bend or shape it. The steel is then specially heated in an oven, and a process called Kolsterising takes place. The Kolsterizing process takes advantage of the fact that the su***ce of the steel become porous, and another hardening compound is applied before the steel cools, whose molecules settle in the steel. This process is another means of hardening the steel even before the DLC coating is applied. By the time the DLC coating is blasted on the watch case, it is already very hard. A reason that you typically don't see watches finished with just Kolsterizing is because it results in a blotchy look to the steel su***ce. The caseback of the Hard Black is not DLC coated steel, though it appears as such. Another metal used on the Hard Black DLC watch is aluminum. If you look closely at the image of the rear of the Linde Werdelin Hard Black, you'll notice holes drilled in to the rear of the watch to allow for unscrewing of the case back.The value in DLC is in its immense durability. One test I read about took a piece of steel that, given a particular type of wear, had a durable life of one week. With a DLC coating, that life was increased to an estimated 85 years. DLC offers at least two types of desirable durability traits. First, is resistance to shock. Meaning that it takes a lot of physical shock to damage, rub off, or dent the DLC coating. Second, is the related concept of scratch resistance; DLC is not only hard, but it is difficult to distort or displace. The natural appearance of a DLC coating is a dark gray, almost black appearance with a slight sheen. To the touch it is very slick (meaning it is also highly water resistant). As an added benefit to germaphobes, bacteria is unable to grow on DLC coatings.Linde Werdelin doesn't just have a DLC coating applied to its watches and call it a day. The process of hardening is very involved with their first DLC watch, the Hard Black Elemental. While these processes are often not publicized, the high costs of many luxury watches can stem from the involved and time consuming processes that must occur to get the perfect end result. Lets go through the process with the case part of the watch. First the case is milled out of 316L high grade steel.