In applying oil varnishes to different objects, various defects often make their appearance, these are in many cases very obscure in their origin, although painfully obvious in their effects. The defects may arise through faults in making the varnishes, through defects in the surface of the objects which have been varnished, through faulty methods of application, or through climatic changes. Seeing, therefore, that there are so many factors which produce defects in varnished surfaces, it is no wonder that the causes of such defects are obscure, especially as the varnisher may be of an unobservant character and fail to notice faults at the time the varnish is being applied. Cracks and pinholes: 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 the cause, and what will do for one case will not do for another. The varnisher should, if he wants to produce a good job, take every precaution to prevent defects arising, for in this case an ounce of prevention is worth a ton of cure. He should see that his varnish is of good quality, that his cans and brushes are in good condition and clean, that the surface he has to varnish is in proper condition, free from grease, dry, and having a smooth surface.

He should never attempt a job in wet or damp weather, and he should take care that, after varnishing, his work is not exposed to any bad influences which will retard the drying and hardening of the varnish.