Part of the charm of block printing is the image that is not quite "perfect". If you want a perfect opaque image you silkscreen. Also for consistant results with block printing a press is desired. We always used a clean brayer on the back of the print to make the contact with block/ink/paper. As for tessellations, we actually DID do tessellations, and then made them into linoleum blocks and printed them. They came out great.