FIX WITH SHELLAC

Fix with shellac refers, in horology, to the action of temporarily securing a component using Shellac, a natural thermoplastic resin secreted by the Asian scale insect Kerria lacca. To fix with shellac a part — typically a ruby / jewel of Pallet stone of Pallets (lever) or the impulse pin (roller jewel) of the Balance — the Horologist (watchmaker) places a flake fragment of shellac on the support, heated on a hot plate or over a flame, until the resin melts (around 65-80°C) and becomes viscous. The part is then precisely positioned with tweezers, then held motionless until fully cooled, which makes the fixation solid. This thermoplastic bonding differs from synthetic adhesives by its reversibility: a simple reheating allows one to To remove shellac the piece without resorting to an aggressive solvent or risking damage to the surfaces. The amount of shellac used must be carefully measured: an excess overflows onto adjacent surfaces and must be removed with isopropyl alcohol before any further operation, otherwise it risks contaminating nearby pivots or jewels. Despite the rise of modern adhesives, fixing with shellac remains a reference technique for reversible Escapement repairs.