The principal difference between oil and distemper painting is, that in the latter the colours are ground in water, and diluted with size. It is much less durable than oil painting, but is cheaper, and is not attended with much smell: it will not bear washing. Ceilings are generally distempered, and walls very frequently. There are several colours used for distempering that will not do for oil, as it would change them. The principal are, - common spruce ochre, common indigo, rose pink, brown pink, blue verditer, green verditer, mineral green, and Saxon green. Whiting is the substance mostly used in distempering. It should be broken and thrown into a vessel of clean water, and left to soak for a short time without stirring it - half an hour is sufficient; the surplus water is then poured off from the top, leaving only the softened whiting, which should then be stirred, to ascertain that there be no lumps in it. To this is added hot durable size, in the proportion of one pound of size to three pounds of whiting; it is then to be well stirred, and left to chill or congeal in a cool place. In summer weather it should stand over night, when, if it is like a weak jelly, it is fit for use.
If it is to be a tinted colour, the colouring substance should be added to the whiting previous to the size being mixed with it. Distemper colours dry much lighter than they appear when first laid on; consequently, it is better, before mixing the size with them, to colour a slip of paper and dry it, to ascertain if it is of the desired tint. In distempering old walls or ceilings, it is necessary that the old distemper be first washed off with an old brush and plenty of water. The holes, cracks, and damaged places, should be made good with plaster of Paris, or distemper putty, made of powdered whiting and double size. They should then have a coat of clearcole made by adding a kittle more size and water to the finishing colour, and using it warm. When this is dry, the finishing colour may be laid on. For new walls, it is only necessary to clearcole and finish.