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Decorating Defects - their cause and cure

White Marks on Polished Wood

Most people are familiar with the white marks which appear on polished wooden surfaces as a result of allowing hot plates, etc., to stand on them. These marks are caused by the heat softening the polish and the condensed moisture which forms is imprisoned underneath the film.
If the marks are not too pronounced and if treatment is attempted soon after they have appeared, they can sometimes be removed by placing a pad made of three or four thicknesses of thick white blotting-paper over them, and then applying a warm iron to the pad. The heat softens the polish and the paper absorbs the moisture.
The paper should be moved about from time to time, or a clean pad substituted, as the moisture is drawn up. The iron should be only moderately hot, or the cure may be worse than the disease. When the treatment is completed, rub well with refined linseed oil and'then repolish.

Yellowing of White Paint

The tendency of white paint used for interior work to assume a yellowish cast is sometimes the source of a good deal of annoyance, but the fault is one which the decorator can seldom control or take steps entirely to prevent. White enamel, made on a zinc-oxide base, will tend to yellow slightly in course of time, if applied directly over a coat of white lead; for this reason, the last coat under the finish should be an undercoat formulated for use under the enamel.
White paint when fresh will usually appear very faintly yellow, especially if it has been in the container for any length of time.
If, however, it is applied to a surface exposed to strong light, the latter will bleach it ' out in the course of a few days. Conversely, the absence of light will increase the liability to yellow.
Repeated washing of painted surfaces with alkaline materials will also encourage this tendency.
It is sometimes assumed by decorators that the use of bleached linseed oil will overcome the difficulty; this, however, serves but little purpose, since the absence of light will tend to yellow even the bleached variety. Some painters try to counteract the discoloration by the addition of stainers such as Prussian blue or lampblack, but this measure is rarely successful. Prussian blue gives a slightly greenish cast, while lampblack makes the paint a bluish grey.
Adulterated oil is often responsible for the fault, and care should be taken to ensure that only pure oil is employed. Gloss paints are naturally more subject to yellowing than semi-gloss or flat, since they contain a greater proportion of oil.
By reducing the proportions of linseed oil in the finishing coat, substituting instead a good mixing varnish, the trouble can usually be avoided. Most of the high-grade synthetic paints remain white in almost any circumstances, and where the retention of absolute whiteness is essential they may advantageously be employed.