Oak furniture is strong and valued for its large, open grain. When you remove the old finish from a piece of oak furniture, you have numerous options for refinishing this beautiful wood. All refinishing begins with light sanding to even out the surface, and cleaning with a tack cloth to remove dust; light sanding between steps helps maintain a flat surface for the next coat of finish.
Traditional finishes start with a sealer. Shellac or varnish mixed in equal part with turpentine are traditional sealants. Synthetic varnish, acrylic or urethane finish and penetrating stains are "self-sealing" finishes; apply them as the seal coat and again as the top coat. Although considered optional by many who work with oak, grain is sometimes "filled" after sealing with a paste thinned with stain or paint thinner. Brush the filler along the grain and wipe across the grain with a lint-free cloth to make a flat surface.
Craftsman artists used fuming to emphasise quarter-sawn oak's grain and the medullary rays that ran along it. After sanding and sealing, the wood was exposed to ammonia, which oxidised its tannins, darkening the wood. Fuming many pieces is problematic, but single pieces can be fumed by the home craftsman using a large tent of black plastic outside in the sun. Commercial ammonia with a concentration of at least 10 per cent, like the kind used for art or old-fashioned blueprint work, fumes faster than household ammonia. After fuming, air out the wood, allow it to dry and apply linseed oil to further darken the finish. Rub in the oil and allow it to dry thoroughly; then add a second sealer coat. Craftsman furniture makers often add a dark glaze after the second seal coat to further highlight the grain. Finish the piece with good furniture wax.
Stains and Glazes
Pigmented oil stain or penetrating oil stain are also popular oak finishes. Water-based stains are used only on new wood and swell the grain. Glazes are pigments mixed with a varnish to emphasise grain. Both are applied by brush along the grain. Wipe along the grain with a lint-free cloth to remove excess stain. Raw sienna and burnt umber pigments are used on dark oak; raw sienna and raw umber are used on light oak. Finish pieces with wax, varnish or acrylics.
Dyes are composed of pigments made by boiling assorted woods with a "mordant," a combination of compounds and chemicals unique to each colour. Apply dyes over a sealer for deep, brilliant colours. Each dye batch will be a bit different, so the adventurous refinisher would be well advised to get advice from a craftsman versed in dyes for wood before beginning.
It seems a shame to cover up the beautiful open grain of oak with paint, but if the furniture is pieced or cheaply made, paint may be the sensible option. Seal the wood carefully and fill the grain to provide a flat surface for painting. Apply acrylic or oil paint in several thin layers.