To straighten a thin oak panel that lias much twisted since the polish was applied, place it face downwards, under pressure, with several thicknesses of paper intervening to protect the polish. If cramps are not available, on the workbench screw pieces of wood which will well overlap the corners. Slack out the screws. Give the back of the panel several coats of spirit varnish or polish. Apply liberally with a brush, taking care that the polish does not run over the edges and spread underneath. "Whilst still wet, apply pressure by tightening the screws, which should be fairly strong. Repeat the operation if necessary, and secure the panel in its place, when straight, by nailing strips of wood around its outer edges.