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Decorating Defects - their cause and cure

Exudations

In certain circumstances, surfaces finished in paint or oil-bound water paint may exude drops of gummy matter, similar in appearance to those often found on knotty or resinous wood.
These exudations are due to partial decomposition of the binder, and the conditions most likely to produce them are badly ventilated rooms in which there is a great deal of condensed moisture, especially if the latter is deposited on the film soon after application, before the finish has had time to dry and harden properly. The defect is more liable to occur over impervious grounds than over those which have an average amount of porosity.
Alternatively, the trouble may be brought about by the presence of free lime within the wall structure; this attacks the oil or binder and makes it soft and sticky, although, as a rule, the effect of this attack is seen in larger areas and only comparatively seldom in drop form.
If the exudations are small and steps are taken to deal with them as soon as they appear, it is often possible to wipe them away with a clean cloth and warm water. On new alkaline surfaces, however, large areas are often affected and the exudations frequently accompanied by discoloration, blistering, and other defects, so that complete removal of the paint is the only possible treatment.