Because Gottlieb used water based inks when they originally silkscreened their backglass artwork. This was a constant for all Gottlieb backglasses which used silkscreening. Though easy to work with, water based inks don’t wear well, and certainly aren’t UV resistant. Because of this, fading is common. And below is a classic example of what happens when a Gottlieb backglass is exposed to sunlight, on this 1975 Gottlieb Goldstrike (add-a-ball version of Eldorado).
There should be a lot more red there! The glass really looks washed out, and our customer wanted this repaired. So we scanned in the backglass and did some corrective work to the colors. Note the colors in the words “gold strike” and the ball numbers across the bottom of the glass. Also notice the main cowboy’s vest. Even the mountain where the three miners are standing at the right had faded from a brown to a green!
The result was pretty dramatic, taking a glass that was faded and dull, into something that shows the colors the way they were meant to be seen. Of course we also had to do the rear mask for the glass, but that was easy work, compared to fixing the front!