The following oak finishes, when done the accepted way, do not require any filler, but are finished over the stain: Fumed oak, Flemish oak, Jacobean oak and weathered oak and mission oak.
WHITE PORE FILLER
Silver, French or Kaiser gray oak finish can be made by staining with a light gray or brown oil or water stain and then filling with a white filler. A thin wash coat of white shellac, about one or two pounds of shellac gum to the gallon of alcohol, can be brushed over the stain. After the stain is thoroughly dry, fill with the white filler. The shellac prevents the moving of the oil stain (oil stain is commonly used on oak finishes) when the filler is brushed on.
USE OF NATURAL FILLER
Natural oak finish requires a natural filler, the color of linseed oil, which is thinned and applied the same as any other filler. Many finishers prefer to buy the natural filler and mix their colors in oil with the filler, or if quick drying results are desired, colors ground in japan dryer can be used. This use and practice is the result of many different color combinations and a variety of finishes, so that it would not be economical to buy a different filler for each finish, as little of the filler would be required.
TESTING FILLER FOR SHADE
In testing out filler for shade it is an excellent idea to stain a piece of wood similar to the one you are to fill, with the same stain, at the time you are staining the larger piece. When yon are to test the filler for shade, which should be as near a match to the stain as possible, apply the filler to a small portion of this and in about an hour brush over a coat of shellac, overlapping the part now filled. Any material difference in the shade should be corrected by adding color or using a lighter filler. Trying to tone out the color in filler is a dangerous undertaking, as too much thinner Mill allow a quick precipitation of the silex and color, and a good filler job is not possible when filler is too thin.
Most prepared fillers are furnished with directions as to the amount of naphtha to be used to the pound of filler, but if no directions are supplied, one can thin to the consistency of a thick pea soup and just thin enough to brush on freely. Such surfaces as gum, birch, beech, maple and the evergreens do not need much filler, if any, and the filler should be made much thinner for these woods than for oak, mahogany or walnut. Most finishers shellac the first named woods after the stain coat and use no filler, as the pores are very small in these woods.