Paragraph 58. The varnish finish is one of the best known of all wood finishes. Some of the very cheapest furniture is treated with an inferior grade of varnish. The customary way of finishing inexpensive furniture is to brush on a thin coat of cheap varnish and allow it to dry and consider the job finished. Such a surface is always unsatisfactory for it is easily marred and does not present any great beauty. To prepare a satisfactory varnish finish, the foundation must be built up as has been previously explained. That is, the wood must be made a desired color with the stain or dye, and the filler must be applied so as to fill all the pores of the wood. Sometimes a cheaper grade of varnish is applied instead of the filler.
There are a great many kinds of varnish, some of which are very cheap and worthless and with which no amount of skill and painstaking would produce satisfactory work. They scratch easily and leave a white, dusty mark when scratched. You can always tell cheap varnish by scratching it with a piece of metal and noticing the white scratch and the dusty appearance. The finest grades of varnish do not leave such a scratch. The best varnish is made of copal gum which is imported. This gum is dissolved in turpentine. A good grade of varnish is expensive but will prove cheaper in the point of service than some of the less expensive varnishes. Varnish should be evenly and carefully spread with a soft brush and with a long smooth stroke. It should be thin enough to flow smoothly from the brush. Great care should be exercised not to allow the varnish to run down the corners nor to accumulate in the angles or low places of the work. Varnish can not be rebrushed after it begins to dry.
Varnishing should be done in a room which is clean and perfectly free from dust. The temperature should be about 75 to 80 degrees. Varnishing can not be done with satisfactory results in a cold room, neither should the varnish be allowed to chill until perfectly dry. You can not do satisfactory varnishing in your manual training shop where dusty work is being done. There should be a separate room free from dust and dirt and of even temperature if you expect to do varnishing. When the first coat of the varnish has had ample time to dry (which should be several days), then it can be rubbed down ready for the second coat. Varnish may feel dry to the touch after it has been on a few hours, but this does not mean that it is thoroughly dry. A second coating of varnish should not be added until the first coat is absolutely dry. This will require from four to seven days, depending upon the kind of varnish and drying conditions.
The first coat of the varnish should be rubbed smooth. This should be done with ground pumice stone and water. A rag should be dipped in water and then in the powdered stone, and rubbed on the surface of the varnish. If the varnish is satisfactory the water will not damage it. The rubber for this purpose is often made by taking a strip of cloth about an inch wide and rolling it up very much as a tape line would be rolled. A string is then tied around it and this pad is used for the rubbing purpose. Sometimes linseed oil is used as a rubbing liquid.
When the first coat has been rubbed smooth then the second coat should be applied. This coat is added in the same manner as the first coat, carefully brushing the varnish smooth and avoiding the possibility of its running or accumulating in the corners. The second coat should be given from five to seven days to dry, after which it should be rubbed down exactly the same as the first coat was rubbed. A third or fourth coat may be added if desirable, and each coat should be carefully rubbed. The final coat should be rubbed with the pumice stone and oil or water until it is perfectly smooth. If a high gloss is desired, such as is found on a piano or automobile bodies a finer rubbing material, such as rotten stone and water or oil, should be used. The careful rubbing with rotten stone will bring out a magnificent finish. You will observe that it takes considerable work to produce a beautiful varnish finish. One reason why so many people fail is because they are not willing to spend the time and the effort necessary. Sometimes varnish finish is left just as it comes from the brush without any rubbing. Possibly this is the varnish with which you are the most familiar. This leaves a sort of cheap-looking gloss on the surface and is not to be recommended for a fine piece of cabinet work.
If you will follow these directions you should in a little while be able to produce a surprisingly beautiful finish, but it will require thoughtful, painstaking efforts.