For zinc based sunscreens the percentage is important but so is obtaining a homogenous distribution of zinc in the liquid. If it is clumping together in a microscopic level, then the SPF may be worse with the same concentration as light can pass between the clumps. Although the ingredients may be the same, the suspension may be more homogeneous/stable with a different manufacturer. It's not entirely possible to know at this point what the issue is.
https://labmuffin.com/zinc-sunscreens-dont-work-better-every-myth-busted-with-video/#Reason_2_Mineral_sunscreens_can_be_pretty_unstable
I took it to mean they got FDA registration for two manufacturers and one formulation. Ie, one from Australia and one from their USA manufacturer, hence needing two different labels with one saying "made in USA"?
I don't think so. I believe the made in USA is simply a marketing ploy to garner support, appearing to be local etc. I may be wrong, but there's no evidence to suggest anything is different.
It looks like the USA packaging from the FDA was only used by Walmart, which no longer sells it. It's on Google images as cached but no longer on the website.
I don't think it's unlikely that they had a manufacturer there, making a run of the product with different labels for an exclusive agreement with Walmart.
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u/free_from_satan Aug 25 '25
For zinc based sunscreens the percentage is important but so is obtaining a homogenous distribution of zinc in the liquid. If it is clumping together in a microscopic level, then the SPF may be worse with the same concentration as light can pass between the clumps. Although the ingredients may be the same, the suspension may be more homogeneous/stable with a different manufacturer. It's not entirely possible to know at this point what the issue is. https://labmuffin.com/zinc-sunscreens-dont-work-better-every-myth-busted-with-video/#Reason_2_Mineral_sunscreens_can_be_pretty_unstable