Pictured in this listing is a backglass with no color silkscreening, just black ink on clear glass. The artwork is different than the production backglass art. We asked former Williams employee Duncan Brown to identify and explain this item. He replies:

That's a "keyline" version of the glass. For both glasses and playfields I've seen keylines done (sometimes on the wood or glass, sometimes just on a large sheet of mylar or paper). It's a cheap and easy early check method for the art. For instance, in the case of a backglass, it is used to make sure that all the score display holes line up properly, before going to all the extra work of cutting the color screens and printing the glass. If you look at any playfield or backglass, you can see that there's always a keyline layer (first one printed on a glass, last one printed on a playfield) that traps the separate colors, gives some edge definition to the art near blank areas, contains the text messages, etc. That pencil sketch of the Vagabond backglass I sent you is essentially a keyline. I'm kind of surprised that one that old lasted all these years. By and large they were something to be used during the design process and then discarded. Interesting too that the art completely changed! I guess that's another reason for a keyline - to make sure that The Powers That Be like the direction the art is headed...

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