Wood well prepared, oak or mahogany, is very durable: the Dutch have prepared them with whiting and size, which has been the destruction of many fine pictures. Van Goyen and others have prepared or filled up the pores of the wood with their transparent vehicle, which also enabled them to shew the grain of the wood through the shades of the subject; but the best way I have found, after trying everything, is this: -Procure at a colour-shop a quantity of what is called by the house painters 'flatting'['italics'], which is white lead ground with a large proportion of spirits of turpentine; stir a small quantity of drying oil well among it; then take as much as will do for present use, and mix it to a proper consistence with spirits of turpentine, and lay on the pannel with the brush, leaving the brush marks the same way as the grain of the wood. When dry, in a day or two, take some of the stiff colour, and plaster it all over with a palette knife, and take it off again as clean as possible with the knife, and sufficient is left to fill up the pores of the wood and marks of the brush. This, repeated two or three times, leaves a most beautiful face, and very hard, and it will never crack or separate from the wood whilst it endures.