The quality of a line is a measure of its sharpness or crispiness. In drafting, a line with a sharp and dark outline is said to be of higher quality than a line with fuzzy and lighter outline. The aim always is to get sharp lines to convey the intended technical message that you want the drawing to show. The quality of a line is determined by 4 factors:
1. The grade or weight of lead: Lead weight is graded from very hard 9H to very soft 9B. Select the appropriate grade of lead that suits your drafting needs. For example, you should select lead grade 2H or 3H for line work and HB and 2B for lettering work.
2. Pressure applied: The pressure applied while drawing controls the darkness of a line. By maintaining a uniform pressure while drawing will produce a line that has a uniform dark outline – sharp line. If a uniform pressure is not maintained, lines will be uneven.
3. Sharpness of lead point: The sharpness of the lead point affects the crispness of a line. Sharpen your lead pencil to form a conical shape. Gradually rotate your lead pencil as you draw to maintain the lead point shape.
4. The angle of the pencil to the straight: While holding the pencil in position, place it away from you such that it is more than 90º. If the angle is less than 90º, the pencil lead will ride on top of your straightedge instead of the bottom. In essence, use the bottom of your straightedge to make your lines.
The Golden Rules for Line Drawings
1. Keep the pencil at an angle to the straight edge. As you hold your pencil, tilt it away from you while leaning it to the right. You want to place your pencil such that you can see the line you are drawing.
2. Pull and draw in the direction the pencil is leaning. You should never push to the direction you are drawing, always pull.
3. Rotate your pencil as it is being pulled so that the lead will wear evenly and maintain equal line thickness (width).
4. Start and end line abruptly so that you do not end up with lines dragging beyond intended start and end points. To achieve this, know where you want to start and end a line before you begin drawing. This practice will keep your work neat and tidy.
5. Keep your pencil sharpened regularly so that variation in line thickness is not noticeable except where intended.
6. Always steady your T-square in position against the side of the drafting board.
7. Draw lines not intended to be shown dark with minimum applied pressure.
8. When drawing with a compass, hold the grip end steady and firmly in position while rotating the drawing leg.
9. Use the correct instrument for drawings that would help to convey the intended information.
10. Keep your drawing and workplace neat and tidy always.