As it is by no means easy to remove pencil-marks from vellum (and indeed it is never wise to attempt it, for the black-lead unites with the animal fat, which can never be entirely got out of the material, and rubs under the action of Indian-rubber or bread into a greasy smudge), it is always well to set out the design in the first instance upon drawing-paper. The best mode for good work is to complete the outline on drawing-paper, and then to trace it carefully with a hard pencil on a piece of tracing-paper, about one inch larger each way than the entire surface of the vellum; then cut out, the exact size of the vellum, a piece of tracing or tissue paper, rubbed evenly over with powdered red chalk.[116] Lay the tracing down (pencilled side upwards) in its right place upon the vellum, and fasten down one edge with pins, gum, or mouth-glue. Then slip the transfer-paper, with the chalked side downwards, between the vellum and the tracing until it exactly covers the former--touching the back of the transfer-paper with two or three drops of gum on its margin. Then lay the tracing over, and fasten down another of its edges. The gum drops will prevent the transfer-paper slipping away from the tracing-paper, when the drawing-board or strainer is placed upon a sloping desk or easel. Taking care to keep a piece of stout card or pasteboard under the hand, go over all the lines of the tracing with a blunted etching-point, or very hard pencil cut sharp. This having been done, on removing both the tracing and the transfer-paper, it will be found that a clear red outline has been conveyed to the surface of the vellum. At this stage of the work, as nothing dirties more readily than this material, it will be well to fasten over the surface a clean sheet of paper with a flap cut in it, by raising up and folding back portions of which, the artist may get to the part of the surface upon which he may desire to work without exposing any of the rest. As the effect of the writing on the page gives as it were the key-note for the general effect of the illuminated ornaments, it will be well to complete the former before proceeding to the latter.[117]