Once again, congrats on a great buy!
In the above pic, with the neon on, you can see the streaks in the light blue area from weathering.
It was outside.
Someone b4 u must've tried to clean it up some and probably sealed it with some wax so the rust would not come out anymore.

LOOKING-4:WELDING SIGNS,Charter/Finance/PulOil/Trulite/TruTest-Oils,True's gas CORALINE/RAINBOW, Gardner 70 items of Yakima wa., Wa/Or/Id Chief items