When I began lettering comics in 1977, nearly every interior page was lettered on pencilled original art. Cover lettering was done on separate paper, then photostatted and pasted on the cover art along with all the other trade dress.
Some time in the 1980s, art began to be lettered on vellum overlays at least some of the time. There were two main reasons for this. One, if it was painted art, there was no other option. Two, if the artist was running late (very common), the lettering could be done on vellum laid over photocopies of the pencilled art, allowing the lettering and the inking to be done at the same time. When the DC Production department had the finished art and the lettering overlays, they would photostat the lettering and paste it onto the art. This became more and more common as time went on. Originally a premium was paid for lettering on overlays, possibly as a way to discourage editors from doing it by adding extra cost to their budget, but that went by the wayside over time. By the early 1990s I would say at least half of my lettering was on overlays.
In the early years of overlay lettering, when asked if I wanted my lettering vellums back, I would say, “No, just throw them away.” Some time around 1993 I decided to start accepting them back as art returns with the idea that I could sell them at conventions or by mail. Over the next ten years or so I accumulated several thousand pages of these lettering overlays, and did sell some from time to time, though they were never in any kind of demand.
When the switch came to digital lettering, of course, hand-lettering on either original art or overlays declined, and I think the last ones I received were from around 2003. And I never made a point of asking for them, but if someone decided to return them to me, I’d take them.
When I launched my website in 2007, one of the categories on my BUY STUFF page was vellum overlays, in lots of 5 or 10 pages. Originally there were about a dozen titles offered, plus grab-bags of miscellaneous items. They sold steadily. As of yesterday I was down to two titles. Today I received a large order for these overlays that essentially wipes out my remaining stock. A few examples from DEATHBLOW #11 (cover dated Dec. 1994) are above. They’ll go out to the buyer Monday, and vellum overlays will no longer be offered on my website. End of an era!