I don’t have any bottles left marked 15 cents, but I actually just used a bottle of Pactra marked 19 cents that I had bought in the hobby center at an Air Force base in Thailand in 1974! By coincidence the shade of olive green is just right for one of the weathered FS colors on the model I just built which was of an F-4 I worked on. I thought I had nothing to lose by checking the paint out so I got my pliers and unscrewed the cap. I found that the paint has thickened somewhat, but had not coagulated. I added Testors enamel thinner then filtered it and the stuff airbrushed beautifully!