I have searched high and low for the answer to this. Everybody must know it but me. I am using the Line Tool to try to draw a 1 px wide black (#000000) line. That worked fine, except that it is either anti-aliasing or doesn't have an opacity of 100% and is coming out dark grey. If I draw a black line over it again, it gets darker, but is still not black. The Line tool is not one of those tools that has an opacity setting at the top, like some others.
Can someone tell me what is going on and how to do this?