Page:Cyclopedia of Painting-Armstrong, George D (1908).djvu/389

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381
VARNISHES

these are often due to climatic changes, especially liable to occur in winter time, when a cold day will follow a hot or warm one. Keeping the object in a warm place for some time will tend to cure this fault, and take care that the varnish cannot get chilled while drying. Peeling, blistering, spots, and crawling are defects which may be traced to a greasy nature of the surface on which the varnish is applied. This may be due to the use of bad pinning, paint, or rubbing the work down with oily rags, or to drops of oil on the surface on which the varnish is applied, and not properly removed in the preparing operations. The remedy consists in preventing the application of oily matters to the surface, and to see that they are thoroughly removed. Sagging: this defect arises from two causes, a very greasy nature of the surface, or from applying the varnish too thickly. The varnisher is tempted to take up too much varnish on his brush, and unless he takes care to spread this well he will leave it too thick, and then sagging or running down may occur. If in the preparatory processes too thick a coat of paint is put on, the varnish may tend to soften this, and then this defect is liable to occur. Sweating and blurring may be due to defects in the manufacture of the varnish, the gums used have not been properly melted and too much of their volatile constituents left in, or the varnish may have been sent out before it was properly matured. Varnishing on a damp surface will also develop these defects. Deadening may be due to faulty preparation of the varnish, but more often it is due to climatic conditions, varnishing in too damp an atmosphere, on damp surfaces, in the presence of deleterious gases and vapors, too porous a subject, too large a proportion of driers used in making it, all of which tend to cause loss of lustre in a varnish, either immediately or after a time. It is difficult under these circumstances to point out a remedy, for one will scarcely know the exact cause in any particular case, and of course it is obvious that the remedy will vary with