Washoe light or Washoe dark?

There is some discussion between Maria and Teresa about the chimpanzee subject they are drawing.

...

Maria: I like your soft pencil touch…

Teresa: Mmm. Why you doing yours in pen?

Maria: It’ll show up better.

Teresa: There you go again. Wanting everything in black and white.

Maria: It’s just your subtle shades might not seen on the page and be lost in the gray background.

Teresa: We’ll see, won’t we? Or are you saying you’ve got to shout loudly to be heard in the marketplace?