Lubrication

Lubrication in a watch is a study in contrasts: the going train needs a relatively free-flowing oil to minimise drag across many meshing points, while the pallet-fork-and-escape-wheel interface needs a thicker, stickier grease that stays put under the sliding, high-pressure contact found there, and the mainspring barrel needs a specialised barrel lubricant, or braking grease, formulated to keep the spring's coils sliding smoothly against each other and the barrel wall without seizing. Watchmakers therefore typically keep several grades of oil and grease on the bench and apply each to a specific, deliberately limited set of points.

Oil is applied in tiny, precisely placed quantities using fine oilers, generally to the jewel or pivot bearing rather than flooded across the wheel or the plate. The reasoning is capillary: oil placed correctly stays where it is needed by surface tension against the jewel's oil sink (a shaped recess designed to hold a droplet in place), while excess oil migrates by capillary action across the plate, picking up dust and eventually gumming the escapement or fouling the balance's poise.

Over-oiling is a genuinely common fault, not just a theoretical risk: it commonly causes a watch to run erratically or stop as oil migrates onto the balance rim or hairspring coils, effectively adding drag and mass exactly where the movement can least tolerate it. Under-oiling, conversely, accelerates wear at pivots and the escapement, producing the metal particulate that later shows up as a cleaning problem and, over years, as measurably worn pivot holes.

Different oils age at different rates, which is one of the main reasons watches need periodic full service rather than only oil top-ups: mineral and early synthetic watch oils oxidise and gum over years, especially where exposed to air at the escapement, and by the time this is visible as a rate problem the movement has often already suffered increased wear from the degraded lubricant. Modern synthetic oils have substantially extended typical service intervals compared to mineral oils used through most of the twentieth century, but no watch oil currently used is considered permanent.

As with cleaning, the purpose of learning this material is calibrated expectations: knowing that a watch needs several distinct, correctly chosen and correctly dosed lubricants explains why a proper service is a skilled, deliberate process rather than a single generic oiling, and why 'a drop of oil' applied at home to a sticking watch is far more likely to cause than to solve a problem.