I cut a couple of simple, quick linocuts to demonstrate the difference between black line and white line.
This is the black line block. You can see that I've had to carve on either side of the line I want to print. This requires precise carving to get a controlled thickness of line. There is quite a lot of waste to cut away. When I draw out a design for a black line block, I use a medium thick permanent pen to draw my lines. I then cut on either side of the drawn line.
This is a white line block. I draw it out in the same way as the block above, but I cut directly on top of the lines I have drawn. This works well for images where the detail is sparse and a fluency of line is important. It's probably the easiest of the two techniques.
This is the print from the black line block, printed with brown ink on white paper:
And this is the white line block printed with brown ink on white paper:
Of the two, the first is more successful because it reads properly as a graphic image, with the shadows around the eyes and a strong overall visual impact. The second image (white line with brown background) just doesn't work as the detail around the eyes doesn't make any sense.
The way to get around this is to print the white line block with a light coloured ink on dark paper:
This reads better as an image, but it has several disadvantages. The ink needs to be dense, opaque and even. It needs to be well printed, and it uses a lot more ink. The lines are fine and delicate and run the risk of being filled in with ink.
I printed the black line print with cream ink on black paper just to show how this particular image doesn't work at all because the lines are too chunky. But it's interesting to see how the weight of the line printed in cream creates an annoying kind of visual interference.
However, you can use printing with white or light coloured ink on black paper to good effect, particularly if you think about the lights and darks. This is a little owl chick that I carved for a Christmas card last year:
You can always use a mixture of black line and white line in your linocut designs. Sometimes it is better to have an idea of what colour ink you want to use and think about the paper too. However, it is always good to play and experiment and sometimes serendipity can be a great teacher too.