_How a Paste Filler is Applied._--Paste fillers should be spread on the surface to be filled very liberally with a wide, stiff brush, allowed to stand from five to seven minutes, and then rubbed off with a piece of burlap or a handful of fine shavings or excelsior. But it must not all be rubbed off or drawn out of the grain. This is an easy mistake for an inexperienced worker to make. The thing to do is to rub it in and at the same time leave the surfaces smooth. The surfaces should then be allowed to dry for about twenty-four hours before receiving the final finishing coats.
The importance of a good foundation surface--even, smooth, and free from unsealed pores that would absorb and thus undermine the first coat of varnish--has been explained in the section on filling and surfacing. If this foundation has been well laid, the amateur finisher may enter upon the varnishing stage of his work with confidence; but he will soon learn that there is much call for skill in order to produce the desired results in this part of the finishing process. The selection, preparation, and application of varnish is a special calling, and great skill comes only as the result of experience; but certain main facts and principles are easily learned.
_How a Good Varnish is Recognized._--It is hardly necessary to say that a superior varnish must be clear, transparent, and brilliant. These qualities are always associated with this kind of finish. But durability is also a necessary quality. An expert will, with his eyes shut, recognize a high-grade varnish by its peculiar odour, which is to him an agreeable one. He will at once detect inferior grades by the rank, sharp odour of resin and benzine used in their manufacture. The range of quality and cost in varnishes is probably greater and more varied than in any other finishing material. For fine, artistic work only the best varnish is allowable; and this may be bought for $3.00 a gallon.
_"Sag" and How Corrected._--A good varnish flows easily from the brush, spreads evenly, and dries slowly, thus allowing plenty of time for its proper distribution over the surface. And time enough should be taken to apply an even coat which will not dry unequally and lead to cracking due to irregular contraction in the process of hardening. It is of the utmost importance that each coat be spread evenly over the surface when first applied. Great care should be taken not to brush long in one place. Re-brushing after a brief interval leaves brush marks which are objectionable. Unequal spreading on broad surfaces often causes the varnish to run or "sag." A tendency to sag may be brushed out if attended to promptly. But, if it is not noticed until the varnish has begun to set, the only way to prevent a bad blemish is to absorb the thickening parts of the coat by means of a partly dried brush; and this must not be attempted three or four minutes after the varnish has been put on. By that time it will have become quite well set and a sag will be beyond repairing by any simple means.