Dashed Line option for measurements

[Posebo]

This might be an incredibly stupid question, but as the title says; is there any way to make a line appear Dashed or Dash-dotted when printing a graph? I'm making a presentation of two graphs, but can't use colours to divide them, hence I need one to be dotted or something similar.
I've tried searching the web and this forum, but to no avail. Any help appreciated.

Best Regards:
Posebo

 

[Todd Anderson]

If you pick one dark and one light color, won’t they appear as light and dark grey lines?

 

[Posebo]

Yes, that is right, this is however for a patent, so it’s crucial that it is separable even after many copies.

Edit: Sorry for the short answer, wanted to reply quickly and were slightly busy, but as said a difference between dark and bright unfortunately won't be sufficient as they may get faded after a series of copies, so it must be clear visual difference even if the image were to be slightly faded or distorted.