When Vensim prints it queries the printer to determine if it is capable of printing in color. If it is Vensim prints in color, if not Vensim renders graphical and text information in black and white. Some software drivers for printers that are capable of printing in color indicate that they are black and white printers.
If you have a color printer that is not printing in color go to the Graphics tab of the Global Options dialog (Tools>Options) and select Color under the Color settings for Printer. This will also work if you want to render output with gray scaling to a monochrome printer.
If you want to force output to be in black and white click on the Monochrome selection.
