Hiromasa Wakui（Grand Seiko leather craftsperson）
The spirit of TAKUMI
Master craftsmanship breathing new life into high-quality leather
Grand Seiko creates wristwatches with a beauty rooted in a traditional Japanese aesthetic. The leather straps used for Grand Seiko are selected, designed and made with the same care and attention as is given to the watch itself.
The tone and thickness of the strap and the details of its stitching should of course vary depending on the design of the watch. To realize this, the master craftsmen who make Grand Seiko’s leather straps do everything, the cutting, the skiving, the construction, the stitching, and the stamping—by hand so that each and every strap is made to suit each watch perfectly. Here is a look into the loving care and attention to detail that goes into the straps for Grand Seiko.
Grand Seiko's leather straps made from carefully selected materials
Highest-grade crocodile leather is used for Grand Seiko's leather straps. Grand Seiko does not use ready-tanned leather, but instead carefully selects raw hides ideal for leather straps and, in accordance with the Washington Convention, directly imports them mostly from Papua New Guinea through a trading company. Dyeing, based on the design of the watch, is done after the tanner uses a specialized tanning process to turn the raw hide into leather.
Considered the crown jewel of leathers, crocodile is valued for its scarcity. Its prime feature is the irregularity of its scales, which creates a pattern full of unique elegance. There are two types of scales, square ones and round ones. The materials are prepared with a matt finish or a semi-gloss finish to make the utmost use of the scale pattern and their unique moist texture. A glaze finish can also be applied to give a glossy feel to the surface of the scales. These are selectively applied to give the materials the appropriate finish for each design. Hiromasa Wakui, the master craftsman in charge of the production of leather straps for Grand Seiko, said the following with respect to the attention paid to the materials.
"As the crocodile grows, the pattern of its scales expands, and the hide gains in thickness too.
The leather strap is made to fit the wrist, so unlike other leather products such as handbags, its width and length are extremely short as it is a delicate part. Therefore, we carefully select the smaller raw hides so that the crocodile scales look beautiful on a leather strap finish, and smaller hides also have the ideal thickness for an item to wear on the wrist. Currently, the raw hides used are from crocodiles raised for two to three years, and each selected piece of leather is one-third to one-half the size of those used for handbags and the like. We carefully discuss with the tanners how to apply the most suitable process for the selected design in order to achieve a comfortable fit on the wrist and moderate flexibility."
Master craftsmanship observed in the cutting process that decides the final shape of the leather strap
Once the materials are ready, the leather strap-making process can begin. A leather strap is basically made of three layers: the upper leather, the filling, and the lining leather. Grand Seiko pursues wristwatches with accuracy, readability, beauty and durability. Therefore, the leather straps must have a comfortable feel on the wrist, improving over time as they are worn. To achieve that, the straps are constructed in three layers of natural leather: crocodile for the upper leather, and usually cow for the filling and the lining leather.
There are five processes in making a leather strap: the cutting, the skiving, the construction, the stitching, and the stamping. A special cutting die is used to manually stamp out each piece of crocodile leather to obtain the desired shape. To ensure a beautiful fit when worn on the wrist—the buckle-side strap at 12 o'clock and the guard pin-side strap at 6 o'clock—the craftsman in charge of cutting the leather must consider the characteristics of each piece of leather. He also has to carefully cut it for the fixed ring and the free ring of the buckle side. The materials for the filling and lining are cut at that time too.
Crocodiles have pores near the edges of their scales that look like small holes pierced with a needle. These are integumentary sensory organ pores, part of a crocodile's sensory system, and proof of the leather being from a crocodile. Grand Seiko selects natural leather of the highest quality that displays the patterns of the belly scales of the crocodile, however, because of that, some pieces of leather will have small scratches or scars that occurred naturally. A high degree of craftsmanship is required during the cutting process in order to instantly spot and reject pieces with defects, while at the same time cutting out the parts to match the scales. The leather pieces are then inspected by an expert for imperfections before being moved on for skiving.
Beautiful finish through intricate leather skiving
As all pieces of natural leather are unique and have an uneven thickness, when making a product, it is vital to adjust the thickness of the individual parts. During the skiving process, the thickness of the leather is evened out, and when constructing the leather strap, the thickness of the mounted sections is controlled. In order to allow the sections of the seam to be folded easily, they are skived down to 0.1 mm.
First, all parts that make up the leather strap—the buckle-side strap, the guard pin-side strap, the fixed ring and the free ring—are delicately skived to the same thickness. Next, the edges on the outer ends of the leather pieces are skived. Skiving the edge thinner than the central section is an important point.
"Grand Seiko uses the Rembordé technique to fold the edges of the upper leather under the filling. The robust edges of the crocodile leather need to be skived thinly as otherwise it would be difficult to fold them around the sides of the filling. Taking into consideration the thickness of the folded section while skiving the edges thinner makes it possible to keep an even thickness when the leather strap is being made. The skiving of the edges is a really important process used to give dimension to the strap design," explained Wakui.
Crocodile is not an easy material to skive. Many leathers, such as that from a cow, are stable due to their fiber, making them easy to skive, but for crocodile, a special technique is required to skive the hide while taking into consideration the irregularities of the scales. Skiving the round scales may stretch them, changing their length. For the square scales, the indents are deeper, and if skived too much, they may tear the leather. The master craftsmen have to be very careful and work delicately while skiving. After skiving the lining leather and filling comes the process of construction.
Master craftsmanship behind a superb construction fit for a luxury wristwatch
The Grand Seiko straps are constructed by wrapping the upper leather around the filling, and then bonding that piece to the lining leather with a special adhesive, or in some cases, sewing the pieces together. The most remarkable feature of the strap is its construction, which makes full use of the materials. The construction not only has an elegant appearance but also has a robustness fit for a luxury watch. Because the upper leather wraps around the sides of the strap, the soft curves of the hide soften the silhouette of the whole strap, giving it an elegant feel. Just like for the skiving process, applying the Rembordé technique to crocodile requires an extremely high level of craftsmanship due to the material's unique unevenness.
"Crocodile leather is supple yet highly robust, while the cow leather filling is soft and curved. In order to apply the Rembordé technique on those two materials with different characteristics, heat is applied on the crocodile leather to make it softer and easier to fold. Because every piece of crocodile leather is unique, the upper leather and the filling are different. Each piece needs to be checked in detail and a special press is used to apply finely controlled heat to bond the pieces together," explained Wakui.
Another technique worth mentioning regarding the Rembordé-edge strap is called "kikuyose." This technique, with an extremely high level of difficulty, is used on rounded edges to delicately fold them into radiating, even pleats. The master craftsmanship acquired over the years to execute the Rembordé technique can be seen in the details of the guard pin side of the strap.
Finest details born from careful handcrafting and strict quality control
After the Rembordé upper leather wrapped around the filling is glued to the lining, the strap moves to the stitching process. Stitching can be done by machine or by hand. When done mechanically, a craftsman specialized in stitching uses a sewing machine customized for leather straps, and carefully sews each stitch on the edges of the buckle and guard pin sides. For hand stitching, a specialized tool called a "pricking iron" is used to open holes in the buckle and guard pin sides of the strap. Then, using a waxed thread made especially for hand stitching, all stitches are carefully made by hand. Grand Seiko uses either method depending on the design and concept of the wristwatch.
"Machine-sewed stitches are characteristic for their robustness, beautiful seam and elegant finish. Hand stitching requires a great deal more work, but compared to machine stitching, it makes it possible to use a thicker thread, control the thread tension by hand and, if necessary, increase the stitch strength. The stitching details, including the yarn count and the width of the seam, are all chosen to match the design of the watch. We are using the most appropriate and optimal method," said Wakui.
The last process in manufacturing the leather strap is stamping. An original "Grand Seiko" stamp is used on the back of the strap, stamping it directly by hand while adding heat and pressure. As mentioned earlier, a leather strap is usually constructed in three layers: the upper leather, the filling, and the lining leather. However, depending on the design, greater thickness may be required. In such case, natural leather padding is added to create a four- or a five-layer strap. The master craftsman in charge of the stamping will carefully check the thickness of the strap and condition of the leather to finely control the temperature and pressure to be applied when completing the stamping.
Grand Seiko has strict in-house inspection standards to guarantee the high quality of its leather straps in regards to discoloration, durability, and light resistance. Only items that meet those standards are put on the market. The leather straps, as opposed to general leather products like handbags are, once completed, considered a part of the wristwatch. As such, based on the European Union's Directive on the Restriction of the use of certain Hazardous Substances in electrical and electronic equipment, or RoHS 1, the leather straps are screened for hazardous materials.
Leather strap emphasizing the aesthetic of Grand Seiko while emitting a profound sense of elegance
Grand Seiko’s craftsmanship is as evident in this leather strap as it is in every detail of the new Shizuri-Yuki watch itself. After being tanned, the surface of the raw hide is dyed maroon and then further colored. The entire surface is first dyed black and then the dye is wiped off. Through this process, the black dye only stays in the indents of the square scales. The delicate contrast with the maroon displays a beautiful two-tone color. The wiping is done by hand by the tanners. Depending on how much it is wiped, the density of the dark tone of the indents will vary. As such, the process is finely tuned to create an even finish.
The stitching is done by hand, and this makes the hand-stitched seam stand out with a finish befitting Grand Seiko quality and beauty.
The stitching is all done by hand and therefore requires more time and effort compared to doing it with a machine. To pass a needle and thread through pierced holes on a piece of natural leather the size of a watch strap and obtain an even and graceful seam requires more finger strength than imagined, and is achievable only due to the cultivated craftsmanship of the strap makers. The leather strap complements this beautiful luxury wristwatch, and as if to merge into the flow of time it fits better to the wrist every time it is used, bringing out a deeply tasteful elegance. This is the pinnacle of master craftsmanship perfected over time through tireless devotion.