SAND-BLASTING & SHOT-BLASTING
Sandblasting and bead blasting are two very similar decorations that give a neutral and matte finish. Sandblasting, which is rougher, is mainly used on large clocks on non-functional surfaces and also sometimes on certain parts of tooling. Bead blasting, finer than sandblasting, is used on smaller components such as bridges or plates of wristwatch movements or pockets. Although clearly easier to do than the Geneva ribs or beading, bead blasting has in some cases managed to make a place for itself in high-end watchmaking.
In the 19th and early 20th centuries, decoration similar to bead blasting, but even finer, was sometimes found on steel components of pocket movements and sometimes even wrist movements. Parts such as crown cores or ratchets, typically when these two movements were engraved with wolf teeth, had this type of decoration. This type of decoration was also sometimes found on chronograph components. This decoration was made with powder to make a bit like a mirror polish. The sandblasting and especially the microblasting made its place at the end of the twentieth century and the beginning of the twenty-first century. It has sometimes even managed to impose itself in the high-end although it is a simple decoration to do. This last point is somewhat paradoxical.
Sandblasting and bead blasting is an affordable technique also for small quantities. You can find these machines at affordable prices in second hand and also new. Where it could get a little complicated is that they take up space and also that they have to be used in a separate room. These machines can create abrasive dust which is not good if you want to do for example mirror polishing in the same room. Some independent watchmakers can also share some machines in a spirit of good neighborliness. The limit is not financial but more space and especially to have a separate room for the use of this kind of machine.
Sandblasting and bead blasting are techniques that are relatively rarely seen in industrial manufacturing. This is probably due to the fact that this technique cannot be mechanized so much. One hardly ever sees this type of decoration in annual productions of more than 50’000 pieces.