Pictorico Ultra density

Today I measured (with a 361T UV densitometer) some scraps of Pictorico Ultra that I had been using to half cover step wedges. These were scraps that I had collected over the years; some may be as much as five years old. The density of the scraps were between 0.17 and 0.18. Meanwhile fresh Pictorico Ultra has a density of 0.14. I’m wondering whether (a) Pictorico gains density with age or (b) Pictorico is manufacturing a thinner version of Ultra (shrinkflation). By the way, I keep the scraps in the original envelope between protective sheets, so it’s not out in the atmosphere.

I normally measure it at .11 with the 361T UV) . . . but yeah, I would assume some batch-to-batch fluctuation . . . the less density the better IMO.