Every strap leaving the Casati Milano atelier goes through twelve processing stages. Some last ten minutes. Some last an hour. None are skipped.
I learned this craft by watching artisans work who didn't explain: they showed. What I know, I owe more to my hands than to books. Here, I describe the exact steps — how we do them, with the technical reasons behind each choice.
Leather selection and preparation
It all starts with the side. The side of a hide — bovine, alligator, shell cordovan — is the most homogeneous part, with the most compact and uniform fiber. From the side, I select areas without visible defects: fence scratches, insect bites, variations in thickness. A vegetable-tanned calf side yields three or four good straps. The rest becomes samples or goes to waste.
Vegetable tanning is the only method I use for standard models. It takes weeks compared to the hours of chrome tanning, but it produces leather that breathes, that flexes without giving way, that develops a patina with use instead of deteriorating. I am familiar with chrome tanning. It doesn't interest me.
After selection, the leather rests. At least twenty-four hours at controlled temperature before I start cutting it. Leather that has traveled is leather under tension. Cutting it immediately risks shrinkage later.
Cutting and shaping
I still cut by hand, with custom-made dies. The steel dies are sharpened every six months — a dull edge compresses the fibers instead of separating them, and a strap with compressed edges does not take the finish well.
Shaping defines the taper: the progressive narrowing from the lug width to the buckle. A taper from 20 to 16mm requires a precise linear progression, not stepped. If the taper is irregular, it shows on the wrist — the strap doesn't fall straight and is visually distracting.
The thickness is thinned by hand in the buckle area. Trop épais à la boucle — too thick at the buckle — is the most common defect in industrial straps. It makes the clasp stiff and irreversibly marks the leather.
Hand stitching — Point de Sellier
The saddle stitch, or Point de Sellier, is the stitching that distinguishes a handcrafted strap from a machine-stitched one. It's not an aesthetic matter. It's structural.
With a machine, a single thread goes back and forth through the same holes. If it breaks at one point, the knot slips and the seam opens. With the saddle stitch, two needles and two threads are used, crossing at each hole. If one section gives way, the rest remains locked. The strap remains intact.
I use waxed linen thread — Fil Au Chinois Lin — in thicknesses from 0.45 to 0.8mm depending on the leather. For alligator and exotic leathers, I always use the smallest diameter: the needle hole must be as small as possible to avoid weakening the scales. For cordovan and full-grain leather, I use thicker thread, which withstands the tension of the stitching without cutting the leather.
The stitch length varies between 3.5 and 5mm. Shorter stitches for fine leathers, wider for full-grain leather. Each stitch is pulled with the same tension: neither too tight, which cuts, nor too loose, which gives way. This is the hardest thing to learn. It is only learned with miles of thread.
Edging and edge finishing
The edge of a quality strap is not what you see in the foreground. It becomes noticeable when the strap is on the wrist and the edge reflects light evenly, without smudges, without color variations.
The process is called burnishing. I start with coarse-grit sandpaper to even out the cut, then progressively move down to 600-grit. Between each pass, I apply beeswax or gum tragacanth — depending on the leather — and work with a wooden spatula at moderate heat. The heat compresses the open fibers and seals the edge.
There are straps whose edges show nothing because the edge is painted with a coating that hides the work. You can recognize it by touch: a shiny, hard edge that cracks over time. A hand-burnished edge remains soft and consolidates with use.
For leathers that cannot withstand heat — alligator, ostrich, some types of lizard — I only work cold with prolonged manual pressure. It takes twice as long. There's no shortcut.
Domed Shape
The domed shape is the transverse curvature of the strap — what makes it conform to the wrist instead of lying flat. Not all straps require it. The NATO is flat by definition. But a leather strap for a Rolex Submariner ref. 114060 or a Patek Philippe Calatrava without a domed shape looks like a strip of leather, not an accessory made for that watch.
The domed shape is achieved in two ways. The first is mechanical: the damp leather is worked on a convex form and left to dry in position. The second is structural: an inner layer with a domed profile is sewn in, which maintains its shape even after years of use. I use the second method for high-end custom straps. The mechanical form tends to flatten over time under the pressure of the wrist.
The intensity of the domed shape depends on the watch. A thin dress watch case requires a gentle, almost imperceptible domed shape. A sporty case with a rotating bezel requires a more pronounced curvature to compensate for the height. This is a calculation I make watch by watch.
Quality Control
The final check is not a checklist. It's a reading.
I take the finished strap and observe it in raking light — that low light that reveals every surface irregularity. Then I fold it along the longitudinal axis to check that the stitching does not show asymmetrical tension. Then I wear it on my wrist — my wrist, not a mannequin — to feel how it hangs.
If something is wrong, it's redone. Not fixed. Fixing an already finished strap means intervening on work that stands on its own. Every intervention leaves a trace. I prefer to start over.
Out of a hundred straps I produce in a year, about eight do not pass this check. These are not data to be proud of: they mean eight wasted leathers. However, these are data that tell me the process works, because defects are found before the strap leaves the atelier.
Frequently Asked Questions
- How long does it take to produce a handmade strap?
It depends on the model and the leather. A standard vegetable-tanned calf strap requires between four and six hours of actual work, spread over two days for drying times. An alligator strap hand-stitched with a domed shape and cold-finished edges requires eight to twelve hours. Delivery times for Casati atelier customs are three to four weeks from leather selection.
- What is the concrete difference between machine stitching and Point de Sellier?
It's not just speed. Machine stitching uses a single thread that forms a chain stitch: if it breaks at one point, the thread slips and the seam opens. The Point de Sellier uses two needles and two independent threads that cross at each hole. If one section gives way, the rest remains locked. They are also distinguishable by eye: machine stitching is identical on both sides, while saddle stitching shows a different angle on the front and back — that is the signature of the two threads crossing.
- Can I order a custom strap for my watch?
Yes. For custom orders, I work from the exact watch reference: I have a database of 45,694 models with certified lug measurements. I don't ask "more or less 20mm" — I ask for the reference, verify the measurement, and cut to that. The appointment at the Casati Milano atelier in Via XX Settembre 15 lasts about forty minutes: you choose the leather, define the taper, the stitching, the buckle. Production then takes three to four weeks from there.
If you want to see the available leathers, the complete catalog is in the leather section. If you already have a watch in mind, write to me directly — I will reply.