Howdy folks- Just a quick "heads up" about some of the product offered in Posters. As a 30 yr. plus veteran of the printing biz, I do, indeed, feel qualified to comment.

What you are describing as a "Proof", actually is not at all a proof, but an untrimmed "press sheet".

There was, generally, only one proof generated. Back-In-The-Day, this would have a "Color Key", with consecutive polyester layers, laid in register. Each layer would represent one color of ink to be laid down, be it four-color-process, or "spot color", or a combination of the above.

Press sheets would be far more common than an actual proof, as they would be pulled, by the press operator, as often as 4 or 5 per minute, as the press is running, to be evaluated so that adjustments could be made to maintain production standards. Often a handfull of these would be stored away with the job docket for future referance, or stored with a stash of trimmed sheets for samples. Mostly, though, they wound up in the trash, hence, their rarity.

Also worth mentioning--throughout the sixties and up though the mid seventies, the lion's share of this work was done on one and two color presses. Thus, multiple passes were needed to create full-color repro. This means the spoilage factor skyrockets, and of course even more press sheets needed to be pulled as the pressman got his parameters in place.

By the way- not only am I an old printer, but a collector of rock posters, as well.

Cheers!