Cracks or splits in wood can be glued, providing the glue can be spread fully on the meeting surfaces. The glue should be the strongest obtainable if the trouble is not to recur. Avoid general-purpose glues. Buy one intended for boats and follow the directions, as these glues are strong as well as waterproof. If good penetration of the glue into the split is doubtful, screw across the joint, so the screw head comes inconspicuously on an inner surface. Always drill a clearance hole for the neck of the screw, then a smaller hole for the threaded part. Use a countersink bit to let the screw head in level.
If a glued joint has come apart, do not put new glue on top of the old as it will not bond. Scrape through the old glue to expose wood fibres. It helps to draw a fine saw sideways across the wood to roughen it before regluing. Modern glues do not require tight cramping, but the surfaces have to be brought closely together. With framed furniture, such as a
chair, rope tied across and twisted with a piece of wood to tighten it, can act as a cramp.
If a joint has loosened, but cannot be opened enough to clean and reglue, a strengthening bracket can be screwed on, inside the framing where it cannot be seen. A triangle of wood could be used at the corner of framing under a lift-out seat. Slope the screw holes towards the corner so they draw the bracket in. Metal repair plates can be bought, or an angle bracket, like a small shelf support, can be used in a corner instead of a wood bracket. For a flat repair there are straight and L-shaped plates, already drilled.
A dent in a wooden surface can be brought back level by forcing moisture into the fibres. Hold the surface level and put a little water in the dent. Put a damp cloth over the damaged area and press a hot iron over its centre, so that the water steams and the pressure forces some of this into the wood. Furniture restorers do the same thing with a very hot spoon, which is put into the water. In both cases the process may have to be repeated. Let all moisture dry out, then polish over the wood.