Sometimes the timekeeping of a watch will be very wrong even after a service - several minutes a day. If a watch is gaining a large amount of time, there is a solution - ‘Timing Washers’. These are minuscule and precisely manufactured amounts of material, designed to be added in pairs to timing screws of particular sizes of balances to affect the rate a known amount (usually 1, 2 or 3 minutes per day). You don’t need to be an expert to see from the Witchi Timegrapher below that there is something not right!

In order to fit these washers, a special type of pin vice is used to grip the balance screws.

Once they are fitted, the increase in weight combined with the head of the screw being further from the centre of the balance wheel alters the inertia of the balance such that it slows down. To anyone looking at the movement without a loupe, the change will be almost invisible, but the difference is very clear on a Timegrapher.