Page:Cyclopedia of Painting-Armstrong, George D (1908).djvu/393

Rh showed on one side very badly, while the other side was apparently perfect, the same varnish being used by the same workman. Such a case appears to be somewhat mysterious, the explanation of such cases is probably that the weather was cold, that the door was open during the process of varnishing, which chilled that portion of the surface reached by the cold air.

Varnish manufacturers who understand quite well the nature of their products take care to mature their varnishes by storing them in tanks for months together, and in all well-regulated varnish factories the temperature of the maturing room is kept uniform the year round, for unless this is done the products would vary greatly in use, and give a great deal of dissatisfaction. It will be seen from this that in putting varnish aside it is necessary to store it in a warm place, and to take care that it does not get chilled, if it should become very cold it is well to gently heat it before using it. In piano factories, carriage shops, and in any other places where the varnished surface must be very brilliant and uniform, it is often the custom to take the most painstaking care to prevent any marring of the varnish by cold, draughts, or dust. The temperature is kept always uniform by means of steam or hot air pipes, double doors and windows are used, and sometimes the precautions taken go to the extent that all the air entering the room is thoroughly strained and freed from dust. The workmen have clothes which they put on previous to entering the room. It is not suggested that painters should take any precautions of this kind, but mention is made of the subject here in order to impress them with the necessity of taking the greatest care with varnishing.

There are two additional reasons which give rise to unsatisfactory varnishing. The first is the habit of mixing varnishes. Experienced painters will sometimes assert that they can get a better result by mixing two varnishes together than they could by using only one. There is some