craftgrrl | silkscreening stencil question

I'm going to be doing some silkscreening using photo emulsion... but as it happens my printer cartidge has crapped out and is printing a little light. :(

I was going to print out an image with on a transparancy and use it in the photo emulsion process.

Can I just 'touch up' the image using a black permanent marker? Or is there any other way I can fix up this not too dark image that will work in the photo emulsion process?

I can't get to an office supply store for a new cartidge for a couple of days and overnight Sunday delivery is a little out of my price range haha

thx in advance!