I always find it interesting to compare original art with the printed results. Many times publishers would use the cheapest paper and the lowest cost printer to get their 'zines on the stands. Even when printed in black and white, the original art shines through with more detail than on the printed page.
Here is an example of Ralph Reese's art for his story, "Man-Plant From the Tomb" (!) from WEB OF HORROR #2. He used an illustration board called Craftint Doubletone which enabled the illustrator to create shading using a special solvent that removed the surface of the board to show the tinting underneath. I suspect that the solvent that was used was full of toxic chemicals which is probably why it's no longer sold. This is one wiser case where its better to use a computer for the same effect!
Below are two illustrations that were used on the letters page drawn by Bernie Wrightson and Jeff Jones. The art is done with ink over graphite on Bristol board.