12. Two pin holes, one at each end of the block, will be used as guides when matching the color block to the key block in the printing process. 

13. A proof, in gray ink, taken from the key block (extreme left) is impressed on the blank second color block. This provides an accurate image to follow when engraving. The press, a Poco proof press, made in Chicago in the early '20s, was used as a proofing press by typesetters and printers. 
  
14. The second color block, showing the image of the key block, is engraved with highlights and shading to complement the key block. (See Appendix C, Proofs) 

15. The second color block is finished, and a color proof is taken of it.