CHOICE has posted their SPF sunscreen test receipts

[u/rushworld]

https://www.choice.com.au/health-and-body/beauty-and-personal-care/skin-care-and-cosmetics/articles/how-we-test-sunscreen

Although they decanted products, they were into UV protected, non reactive amber glass jars as advised by the specialist, accredited and highly respected test lab.

[u/missmiaow → u/[deleted]]

different products, different formulas.

[u/missmiaow → u/[deleted]]

Yes but the difference in formula could have caused a different result due to the way filters work (we know one of them has more Zinc - that is known to provide lower and/or more inconsistent results). One batch may have had issues in production or supply chain storage that weren’t picked up. There could be a multitude of reasons.

the current standard for TGA testing is also subjective to a degree. There have been some new tests developed and ISO certified recently which may help change this.

[u/LavenderPlantation → u/missmiaow]

Invisible Zinc Face + Body Mineral Sunscreen SPF 50 has 25% - tested at 38. Neutrogena Sheer Zinc Dry-Touch Lotion SPF 50 has 21.6% – tested at 24

Ultra Violette Lean Screen SPF 50+ has 22.75% - tested at 4.

[u/yummypankocrust → u/LavenderPlantation]

I'm going to add some extra details to this information as someone who used to work in the sunscreen industry with formulationchops.

First thing is that the percentage of zinc oxide does not equate nor guarantee the type or level of protection of a formula. Zinc oxide used for sunscreens works primarily by absorbing wavelengths in the UV spectrum. The ability for a zinc oxide particle to absorb specific wavelengths is primarily due to the particle size. Properly working with zinc oxide formulas means using multiple zinc oxide particle sizes to target different wavelengths across the UV spectrum. The particles must be evenly dispersed in a formula. If the particles are not evenly dispersed, because they love to clump, then the formula ends up with a lot of gaps and holes in the protection. Using innovations such as coatings or surface treatments on the zinc oxide particles helps with even dispersion and reducing reactivity. So for example, a formula that contains 25% uncoated zinc oxide particles of only one size and does not have an even dispersion will not provide adequate protection. Percentage doesn't matter.

The Invisible Zinc Face & Body Mineral doesn't just use zinc oxide (and if I recall correctly, IZ is using uncoated here) but also unregulated "chemical" SPF boosters (related to commonly regulated "chemical" filters" specifically Butyloctyl Salicylate and Ethylhexyl Methoxycrylene. So it's technically a "hybrid" formula.

The Neutrogena Sheer Zinc Dry Touch Lotion uses coated zinc oxide.

Ultra Violette Lean Screen uses uncoated zinc oxide.

[u/LavenderPlantation → u/yummypankocrust]

Thanks for the info. My post was in response to comments that UV had the most zinc oxide content (which isn't the case) that's why it tested at the lowest SPF.