TO REMOVE SHELLAC

To remove shellac consists in softening then dissolving the shellac that holds a watch component in place, in order to release it without subjecting it to mechanical stress. The operation, the reverse of applying shellac, is carried out by gently heating the piece — using a flame, a heating plate, or a shellac-removing iron — until the resin reaches its softening point, around 65 to 80 °C depending on its composition; once the shellac has become viscous again, the component is then carefully removed with tweezers. This is commonly done to remove shellac from the pallet stones of the pallets (lever), the impulse pin (roller jewel) of the balance or other temporarily glued parts, with a view to their replacement or to escapement-making (finishing). After shellac removal, resin residues are eliminated with isopropyl alcohol applied with a wood stick or a fine brush, without ever rubbing the polished surfaces. The operation requires gentleness and gradualness: heating too quickly or locally risks distorting a delicate part, altering a polished finish, or damaging a neighboring component still coated with shellac, and must always be carried out in a ventilated space to evacuate solvent vapors.