Illumination on plaster may be executed either in distemper, if the walls or ceiling have been sized only, or in oil if they have been brought forward in oil-colours. The former is the most rapid, but least durable process. Hence decoration is usually applied in oil to walls which are liable to be rubbed and brushed against, and in distemper, to ceilings, which are, comparatively speaking, out of harm's way. Very pretty decorations on plaster may be executed by combining hand-worked illumination with diapered or other paper-hangings. Thus, for instance, taking one side of a room, say about eleven feet high, to the under-side of the plaster cornice, mark off about a foot in depth on the wall from the bottom of the cornice, set out the width of the wall into three or more panels, dividing the panels by upright pilasters of the same width as the depth of the top border. At the height of about four feet from the ground mark off the top edge of another horizontal band, which make also one foot deep; continue on the lines of the pilasters to within six inches of the top of the skirting, and draw in a horizontal border, six inches high, running all round upon the top edge of the skirting: then paint, in a plain colour, a margin, three or four inches wide, all round the panels formed by the bands and pilasters, and let the paper-hanger fill in the panels with any pretty diapered paper which may agree with the style and colour in which you may desire to work your illumination. The side of your room will then present two horizontal lines--one next the cornice, and one at about dado-height, suitable for the reception of illuminated inscriptions. In setting these out, care must be taken to bring a capital letter into a line with the centre of each pilaster, so that a foliated ornament, descending from the upper inscription, and ascending from the lower one, may meet and intertwine on the pilasters, forming panelled compartments for the introduction of subjects, if thought desirable.[99]