Adequate time must be allowed for the structure to dry out and for the surface to cure.
If the surface is prematurely sealed with an impervious layer of oil paint, the moisture will force the paint off and the plaster may be prevented from hardening properly. If early decoration is necessary it should take the form of permeable material such as water paint or emulsion paint. When drying out is complete, an alkali-resisting primer should be applied before finishing with oil paint.
This must be allowed to dry thoroughly before being sealed with oil paint. The plaster should be chemically inert; alkaline matter may, however, be brought forward from the backing materials or lime may have been added by the plasterer. Before painting, test for alkalinity. If any doubt exists alkali-resisting primer must be used.