The undisputed champion of advertising in the pages of golden age comic books was the Daisy Air Rifle Company. One is hard pressed not to find one of its full page ads when flipping through the funny pages of virtually any random copy from Superman to Red Ryder (who even had his own Daisy Red Ryder BB Gun).
On the business side publishers were obligated to provide proof to customers its advertisements ran. Daisy Air Rifle Company would send the ad to a publisher like D.C., and they would in turn mail back a copy of the comic from the printing presses as evidence the ad appeared (aka “you got what you paid for.”) A staff member of The Daisy Air Rifle Company then pulled the cover off (sometimes with some inside pages), in many cases stamped “Checking Copy” on the cover, and promptly filed it away.
Fortunately a lucky comic dealer located a portion (approximately 240) from a lady in Fayetteville Arkansas who had a mother who worked at Daisy. At some point the company was clearing out the library by throwing them away and allowed employees to have at them. From the salvaged stash the dealer purchased there was no apparent pattern. They range in time over 20 years (from as early as 1939 to as late as the Silver Age (1959)) and while predominately D.C., included other publishers Eastern Color, Dell, Quality, David McKay, Harvey, Pines, Marvel and Fox Feature Syndicate. Genres spanned the whole gambit from funny animals to superheros. The highlight of the find was a Detective Comics #33 cover with “Daisy” written on it. I managed to acquire the ones shown below from the dealer.
One would imagine the true number of Daisy checking copies would have gone well into the thousands. One must assume the lady grabbed a very small chunk and others are either still sitting in a Daisy library somewhere, were tossed out and are now lost forever to time (leaving this find as the sole surviving representatives of the Daisy File Copies) or were grabbed by other employees and are still waiting to be discovered by collectors.