The Golden State: Where & How to Live, Secure, Visit, Enjoy and Thrive in California
Coloring Finishing And Painting Wood
125. Transparent Fillers.—The time-honored process of filling wood was by applying many coats of some dryingoil, usually linseed-oil, rubbing, and allowing each coat to dry before another was applied. This method of filling the pores and protecting the wood was quite effective on all except possibly the coarse open-pored woods; but it was very slow, because such oils oxidize very slowly, and do not harden for a long time. Linseed-oil practically always darkens wood, and is objectionable on some light-colored woods; but it seems to enrich and bring out the grain and beauty of others, as is the case with walnut.
Shellac as a transparent wood-filler came into use later chronologically than linseed-oil. It is commonly used for this purpose on woods that have pores too small to be seen with the naked eye. Some of the close-grained hardwoods, and most of the coniferous woods, come under this classification, and can be sized or given a surfacer of thin shellac. Two thin coats are better than one heavy application.
Shellac is a spirit-varnish which is very transparent and dries hard in about 8 hours, instead of taking many days, as does linseed-oil.4 It keeps the wood in almost the natural color, darkening it but little, and does not obscure the grain, as other fillers may do to some extent.
126. Liquid Fillers.—Certain surfacers on the market, called architectural fillers or liquid fillers, which are not much used in finishing furniture, are suitable to apply as a sizing material for a first coat on many of the rather soft, close-grained woods that have inconspicuous cell-openings.
Less labor is required in the application of this type of filler, because it is painted on much like a coat of varnish, and is not rubbed off. Liquid filler obscures the grain to some extent because the silex or coarse material, altho nearly transparent when mixed with linseed-oil, is stuck to the surface by varnish, instead of being left only to fill the large open pores, as is the case with paste fillers. Liquid fillers are quite commonly used on the less expensive soft woods, when a cheap finish is wanted. They are satisfactory as a first coat on many kinds of wood, especially in finishing the woodwork of houses; but they are not suitable to use on oak, ash, or other woods with large, conspicuous, open pores.
An experienced wood-finisher will usually make one gallon of liquid wood-filler cover about 250 square feet of surface.
The ingredients found in liquid fillers vary greatly, especially in the amount of silica (or silex) and varnish contained. Some liquid fillers are nearly pure varnish with the addition of small amounts of body materials, such as silica or whiting (calcium carbonate), together with some drier and thinner. Other liquid fillers are much like a thin paste filler, with only a small amount of varnish added to the mixture.
