Windows simulates colors and gray shades on a B&W printer using patterns of black dots. For this feature to work as expected, the width used for a given line or curve must be greater than 1 printer dot. For best results when printing colors or gray shades, the minimum line width used for drawing curves should be about 12 dots, or 0.02 inches on a 600 dpi printer or 0.04 inches on a 300 dpi printer. Line widths used for each curve may be changed with the Symbol/Line Styles command on the Options menu, or by selecting the Symbol/Line Styles tool.
Symbol/Line Styles tool.