Two coats of patent knotting or shellac varnish may be given to cover stains, damp spots, or other work which will not take the paint. Even tar spots thus treated may be neutralized.
Grained work should never be varnished until after 6 or 7 days from the time it is finished. This delay will render the surface much more durable than it would be if varnished immediately.
Spring and summer are not the best for painting, as many suppose. The autumn is better, as the work is then, as a rule, thoroughly dry and in the best condition to take the paint.
To obscure window glass, the best plan is to apply a coat of matting varnish, which is specially made for the purpose. It looks very neat, and effectively obscures the glass, although it shuts out very little of the light.
A rough way of testing a brush is to pluck a few bristles and to burn them by applying a match. If they are true bristles they will give off an unmistakable odour, will frizzle up while burning, but will not leave an ash. Fibre, on the other hand, burns without smell, and leaves an ash.