Painting and Finishing Floors

Only enough varnish should be used in the preparation of a good filler to form a sort of paste, and the filler must be thinned down to working consistency with turpentine just before it is to be used. It is applied with a short, stiff brush, and rubbed well into the pores of the wood, across the grain. It is not sufficient to simply apply the filler like a paint. The filler should be allowed sufficient time to set—that is, for part of the turpentine to evaporate—when it is to be rubbed well across the grain of the wood with coarse burlap or bagging. Some finishers use excelsior or curled hair, but these are not so good, as they have a tendency to drag the filler out of the pores. The filler must not be allowed to become bone dry before rubbing, or it will be impossible to rub it at all, or even to cut it down with sandpaper, for the silex and varnish will form a harder cutting surface than the glue and sand of the sandpaper. After rubbing, the surface of the wood must be wiped off with a cloth, in order to remove any surplus filler. Many hardwood finishers make a prac tice of giving a second coat of filler, especially on oak, chestnut, and ash. This second coat of filler lies upon the surface of the wood in a thin, smooth film, as hard as glass, and acts more as a surfacer than as a filler.

Wood fillers are used not only for the pur pose of leveling the surface of the wood, but they serve the additional purpose of bringing out more fully the beauty of the markings of the grain. To this end they are not only used plain, but are sometimes stained or colored with various pigments. Antique oak, for example, is produced by darkening the filler for oak wood by the addition of burnt Turkey umber; golden oak is made by adding Vandyke brown and black asphaltum varnish to the filler; Flemish oak is made by the addition of Vandyke brown, burnt Turkey umber, and drop black; and forest green oak requires a filler stained with lampblack and chrome yellow. Other woods, such as mahogany, walnut, and ebony, are usually filled with a paste filler that has been toned up to match the color of the wood. Many beautiful effects can be produced by means of stained fillers, without any general staining of the wood.

Where a very light colored wood is to be filled, the oil in the varnish with which the filler is mixed might cause a darkening of the wood if the filler were applied directly to the bare wood. Where it is desired to avoid any such effect, a very thin coat of shellac may be applied to seal up the pores and prevent the oil from the filler from sinking into the wood. For all ordinary cases, however, the filler should be applied to the bare wood.

The use of a coat of linseed oil under a finish that is made up of varnish coats is strongly condemned, as an oily undercoat will invariably cause subsequent coats of varnish to peel.

Liquid fillers,

so called, are not properly termed "fillers," because they are not intended to fill up the pores of open-grained woods as paste fillers do, but are intended to be used upon the surface of close-grained woods, such as white pine or whitewood, or as a second coat over a paste filler, for the purpose of stopping suction and producing a smooth and level sur face upon which a subsequent coat or coats of varnish are to be applied. The name surfacer

would be more appropriate for these materials.

At best, they are intended as substitutes for shellac or for a coat of varnish. Prior to their• introduction, shellac was generally used as a surfacer; but this material having become quite expensive owing to the high cost of the gum shellac, these liquid fillers were offered to the trade as substitutes for the more expensive arti cle. Many hardwood finishers recommend using varnish from the surface of the wood up to the finishing coat in the case of close-grained woods, or directly upon the paste filler in the case of open-grained woods. This practice has much to recommend it; for varnish is not affected by dampness, as shellac is, and it would exert no chemical action upon the subsequent coats of varnish, such as some of the liquid fillers appear to do.

Liquid fillers are made usually by incorpor ating very finely ground silex into a good var nish of medium price, and thinning down to working consistency with turpentine or benzine. Those thinned with turpentine are the best. China clay is also used in the manufacture of liquid fillers.

The cheaper grades of liquid fillers are made from cheap rosin varnish, which has a tendency to soften subsequent coats of varnish applied over it. As a rule, cheap liquid fillers are worse than useless.

One of the greatest disadvantages of a liquid filler is that the pigment will in time cause the finish to appear cloudy, as the oil in the filler gradually oxidizes. The greatest value of a good liquid filler is that it is more easily applied than shellac, and is more economical. The pig ment stops the suction of the wood and holds out the subsequent finish better than a priming coat of varnish not containing pigment.

Testing Linseed Oil. The simplest tests for the purity of linseed oil are the smell and the taste. Good, raw linseed oil should be of a light yellow color; a greenish oil usually indicates that it has been made from unripe seed, and is not fit for use in first-class paint. Pure linseed oil, when first placed on the tongue, has a bland taste, turning afterward to slightly bitter and rasping. The presence of either rosin or min eral oil as an adulterant gives a decidedly nauseating taste. A few drops of pure linseed oil rubbed briskly between the palms of the hands should have only the characteristic odor of flaxseed; a faint odor of rosin indicates adulteration with rosin oil, while an odor of machine oil shows the presence of mineral oil. If there is a sweet, mealy smell of fish or men haden oil, it is very difficult to disguise when the oil is heated, but fish oil is little used as an adulterant. If a drop of the suspected oil be placed on a piece of black japanned tin or on a sheet of glass painted black on the other side, the presence of mineral oil will be detected by a bluish iridescence or bloom, when held in a strong light, sometimes extending as a ring beyond the drop of oil.