varnish, which is caused by the oxidation of the linseed oil that is used as the solvent for the varnish gums.
Suggestions for Staining. Modern fashions in wood finishing call for the use of stain even on the hardwoods, such as oak or maple. Many of these stains are intended simply to produce color effect without any idea of imitating some other wood than the one stained. Oak, for example, when finished in the natural color, is too light to harmonize with a good deal of the modern decoration, and it must either be dark ened or its color must be changed entirely. It is by no means unusual to stain oak either a green or a red color, although no natural oak of these colors is obtainable. When it comes to white pine or poplar, these two woods are entirely too lifeless in color to suit the modern taste in decoration, and a stain becomes neces sary. These stains are either pigment stains, which are merely very thin paints made of a semi-transparent pigment ground in linseed oil and reduced with linseed oil and turpentine to the consistency of a wash; or they may be aniline or vegetable stains and dyes, dissolved in water or alcohol; or chemical (acid or alkali) stains that darken or change the color of the wood by acting upon the tannin contained in the wood to form a new chemical compound of a different color. These are the three principal kinds of stains used by the practical painter and hardwood finisher, although occasionally variations of them are employed, such as pig ment stains reduced with petroleum, or aniline stains soluble in oil or turpentine.
Varnish Stains. Besides the above-named classes of stains, there are two classes which are made for the amateur rather than for the practical painter. One of these is the so-called varnish stain, which is made by mixing pigment and varnish together, so that the same applica tion both stains and varnishes. While these are comparatively easy for the novice to handle, the results obtained are far from satisfactory, be cause the pigment is apt to settle to the bottom of the can, and, unless it is kept thoroughly stirred up, the result will show streaky and uneven. A later development of these varnish stains is a varnish colored by means of a trans parent aniline dye, so that a clearer and more satisfactory finish is obtained than by the older varnish stains. These later stains are sold
under various fancy proprietary names, and extensive advertising has created a large de mand for this class of goods. While very satis factory for amateur use, they are not so well suited for the practical painter, because in order to adapt them for household use they are usually made of a quick-drying varnish. The tendency of such a varnish is to show laps on a large surface, and the painter naturally pre fers varnish that is slower drying.
One of the greatest difficulties experienced with stains, especially on such woods as white pine, is the tendency to sink more deeply into the softer parts of the wood, thus making them much darker than the harder portions and pro ducing an unevenness of color tone. To a cer tain extent this assists in bringing out the grain of the wood, but is not always desirable, and various means are resorted to for correcting it. One method is first to give the wood a coat of shellac. Upon this surface a pigment stain will produce a very even color. A well-known Chi cago painter, before using aniline stains, rubs the wood over with a combination of five parts of benzine and one part of raw linseed oil. This prevents the absorption of the greater part of the stain by the softer portions of the wood and gives a more even color tone.
An objection that is often raised to water or alcohol stains is that they raise the grain of the wood, necessitating a subsequent sandpaper ing. As this will take off the little raised nibs, and leave small spots of unstained wood under them, it will usually be better to apply a second coat of stain after sandpapering.
Pigment oil stains are easiest to apply, since they do not raise the grain; but they naturally hide the wood to a greater extent and cause a slight muddiness of tone that cannot be over come with this class of stain. Nevertheless, stains of this character may be made to produce very beautiful effects, at a less cost than with either water, alcohol, acid, or alkali stains.