In Relief treatment the designer is concerned with the effect of Light and Shade in harmonious arrangement of mass and line.
Perspective and foreshortening are permissible to some extent, but are largely dependent upon the work, greater license being allowable in high than in low relief.
In Flat ornament, leaves are invariably in profile, but in Relief expression they may be folded, that is, wrapped round the stem. Greater freedom is possible in the turn-overs.
Relief ornament should recognise ground by details being occasionally displayed in lower relief.
Whether expressed in Flat or Relief, the composing lines should always be emphatic, and their direction traceable through the details, floral or otherwise.
In addition to the foregoing, a further consideration is that of interest of surface, which may consist of contrast in textures of rough surface with smooth, of patterning on form, veining and striation of leaves and flowers, and of the employment of trellis or imbricated pattern. The latter in conjunction with other details, occur in the decorative work of the later French Renaissance.
The technical means of obtaining the interest of surfaces is, of course, incidental to the process involved. If the decoration be the result of painting, the design is free and untrammelled by any other than purely æsthetic conditions. Such, for instance, as the desirable recognition of surface, and the pattern sense suggested by recurrence, if a decorative rather than a pictorial effect is desired.
When the decorations consist of ornament, wholly or partly, they are occasionally rendered in a conventional manner, based upon the appearance of Relief, as in the Pompeian wall decorations and the painted work of the Italian Renaissance. There is ample precedent for this treatment in traditional painted decoration, but deliberate attempts at realistic effects are not only undesirable but to be deplored.
The interest in Painted Decoration, apart from colour, design or subject, would be that of the individual manifestation of the designer and painter.
Stencilled decoration is a compromise between painting and mechanical printing, and is restricted by the unit. The repetition of this is practically mechanical, though considerable license is possible in the treatment of colour, which has to be personally applied and is therefore amenable to controlled variation.