In selecting drawing paper, the first thing to be considered is the kind of paper most suitable for the proposed work. For shop drawings, a manila paper is frequently used on account of its toughness and strength, for these drawings are likely to be subjected to considerable hard usage. If a finished drawing is to be made, the best white drawing paper should be obtained, so that the drawing will not fade or become discolored with age. A good drawing paper should be strong; should have uniform thickness and surface; should stretch evenly and lie smoothly when stretched or when ink or colors are used; should neither repel nor absorb liquids; and should allow considerable erasing without spoiling the surface. It is, of course, impossible to find all of these qualities in any one paper, as great strength cannot be combined with fine surface. However, a kind should be chosen which combines the greatest number of these qualities for the given work. Of the higher grades of papers, Whatman's are considered by far the best This paper, either side of which may be used, is made in three grades: the hot pressed, which has a smooth surface and is especially adapted for pencil and very fine line drawing; the cold pressed, which is rougher than the hot pressed, has a finely grained surface, and is more suitable for water color drawing; and the rough, which is used for tinting. For general work, the cold pressed is the best as erasures do not show as plainly on it, but it does not take ink as well as the hot pressed.
Whatman's paper comes in sheets of standard sizes as follows:
Gap...... 13X17 inches.
Demy ..... 15X20 ".
Medium..... 17X11 ".
Royal ... 19X24 ".
Super-Royal ... 19x27 ".
Imperial . . . . 22 x 30 inches.
Atlas ...... 26 X34 ".
Double Elephant. . 27x40 " Antiquarian . . . 31 X 53 ".
The usual method of fastening paper to a drawing board is by means of thumb tacks or small one-ounce copper or iron tacks. First fasten the upper left-hand corner and then the lower right, pulling the paper taut. The other two corners are then fastened, and a sufficient number of tacks placed along the edges to make the paper lie smoothly. For very fine work, however, it is better to stretch the paper and glue it to the board. Turn up the edges of the paper all the way round - the margin being at least one inch - then moisten the surface of the paper by means of a sponge or soft cloth, and spread paste or glue on the turned-up edges. After removing all the surplus water on the paper, press the edges down on the board, commencing at one corner and stretching the paper slightly - if stretched too much it is liable to split in drying. Place the drawing board in a horizontal position until the paper is dry, when it will be found to be as smooth and tight as a drum head.
The drawing board, Fig. 1, is usually made of well-seasoned and straight-grained soft pine, the grain running lengthwise of the board. Each end of the board is protected by a side strip - 1 3/4 to 2 inches in width - whose edge is made perfectly straight for accuracy in using the T-square. Frequently the end pieces are fastened by a glued matched joint, nails or screws. Two cleats on the bottom, extending the whole width of the board, will reduce the tendency to warp. Drawing boards are made in sizes to accommodate the sizes of paper in general use.
Fig. 1. Drawing Board.
Thumb tacks are used to fasten the paper to the drawing board. They are usually made of steel, pressed into shape - as in the cheaper grades - or with heads of German silver, the points being screwed and riveted to them. For most work, draftsmen use small one-ounce copper or iron tacks, as they are cheap and can be forced flush with the drawing-paper, thus offering no obstruction to the T-square.
Lead pencils are graded according to their hardness, the degree of which is indicated by the letter H - as HH, 4H, 6H, etc. For general use a lead pencil of 5H or 6H should be used, although a softer 4H pencil is better for making letters, figures, and points. The hard lead pencil should be sharpened as shown in Fig. 2 so that in penciling a drawing the lines may be made very fine and light. The wood is cut away so that about 1/4 or 1/2 inch of lead projects. The lead can then be sharpened to a chisel edge by rubbing IT against a bit of sand paper or a fine file, and the corners slightly rounded. In drawing the lines the draftsman should place the chisel edge against the T-square or triangle, thus enabling him to draw a fine line exactly through a given point. If the drawing is not to be inked, but is made for tracing or for rough usage in the shop, a softer pencil, 3H or 4h, may be used, so as to make the lines somewhat thicker and heavier. The lead for compasses may also be sharpened to a point although some draftsmen prefer to use a chisel edge for the compasses as well as the pencil.
In using a very hard lead pencil a light pressure should be used as otherwise the chisel edge will make a deep impression in the paper which cannot be erased. Erasers. What little erasing is necessary in making drawings, should be done with a soft rubber. To avoid erasing the surrounding work some draftsmen use a card in which a slit is cut about 3 inches long and 1/8 to 1/4 inch wide, Fig. 3. An erasing shield of thin metal, Fig. 4, is also very convenient, especially in erasing letters. For cleaning drawings when they are completed, a sponge rubber or a preparation called "art gum" may be used, but in either case care should be taken not to make the lines dull by too hard rubbing.
Fig. 1. Pencil Sharpened to a Chisel Point.
Fig. 3. Erasing Shield.
Fig. 4. Metal Erasing Shield.
The T-square, which gets its name from its general shape, consists of a thin straight-edge, the blade, with a short piece, the head, fastened at right angles to it, Fig. 5. T-squares are usually made of wood, the pear and maple woods being used in the cheaper grades, and the harder woods, like mahogany, with protecting edges of ebony or celluloid, Fig. 6, in the more expensive instruments. The head is designed to fit against the edge of the drawing board, allowing the blade to extend across the surface of the board. It is desirable to have the blade of the T-square make a right angle with the head, but this is not absolutely necessary, if the head is always placed against the left-hand edge of the board, for the lines drawn with the T-square will then be referred to one edge of the board only, and if this edge is straight, the lines will be parallel to each other. T-squares are sometimes provided with swiveled heads as it is frequently very convenient to draw lines parallel to each other which are not at right angles to the left-hand edge of the board. To use the T-square in drawing parallel horizontal lines,* place the head of the T-square in contact with the left-hand edge of the board, Fig. 7, and draw the pencil along the upper edge of the blade at each new position of the T-square. Only the upper edge should be used as the two edges may not be exactly parallel and straight. In trimming drawings or cutting the paper from the board, always use the lower edge of the T-square so that the upper edge may not be made untrue. For accurate work it is absolutely necessary that the upper edge of the T-square be exactly straight To test the straightness of the edge two T-squares may be placed together as shown in Fig. 8. However, a lack of contact such as shown in the figure does not prove which edge is crooked, and for this determination a third blade must be used and tried with the two given T-squares successively.
Fig. 6. Mahogany-Bound T-Square.
Fig. 7. Drawing Parallel Lines.
* See Appendix.
Fig. 8. Testing the Edge of T-Square.