This section is from the book "Arts & Crafts Magazine Vol1-2", by Hutchinson & Company.
The kind of crayon portrait you describe is surreptitiously founded on what is known to the trade as a "solar print," which, for this purpose, is a faintly printed life-size enlargement of an ordinary carte-de-visite or cabinet photograph. It is usually made on Whatman or other drawing paper with " a tooth to it," and mounted on a stretcher. Thus, at a slight cost, the "artist" finds ready prepared for him the foundation of the picture for which he will, perhaps, get a very respectable price, after he has gone over certain parts of it with "crayon sauce," and worked up the details with a little point work by the aid of a lew sittings from the original. A great proportion of the crayon portraits executed from photographs are made in this fashion; and many persons; even, who will indignantly deny that their work is anything but "freehand," will use a very faint solar print to save them the labour of sketching the outline and getting correctly the shadows of the face. Any person of average intelligence can, after a little practice, learn to execute such a crayon portrait; but the proud possessor of this work of art must be careful not to expose it to the light unless he would have it fade out gradually, or turn a reddish tint, and in a few years be a complete wreck.