I genuinely don’t quite know how to write this without getting emotional.
When I first started developing our Pure Mineral Sunscreen, I wasn’t trying to create an SPF 50+. I simply wanted to formulate a gentle, mineral-based sunscreen that fitted everything Farmstead Naturals stands for — simple ingredients, sensitive-skin friendly and something I would genuinely feel happy using on myself and my family.
When I finally sent the finished formula away for professional SPF testing, I was nervous.
I’d formulated it using non-nano zinc oxide, and although I knew zinc oxide provides mineral UV protection, sunscreen performance can’t simply be predicted from the percentage of zinc in a formula. The finished product actually has to perform.
In my head, I was hoping for somewhere around SPF 25–30.
Then the result came back.
64.57.
I honestly couldn’t believe what I was reading.
Seeing something I’d developed and made here at Farmstead Naturals achieve that result genuinely brought tears to my eyes.
It wasn’t just a number. It represented all of the formulation work, testing, worrying, researching and questioning that had gone into creating this product.
And a measured SPF of 64.57 places the product within the SPF 50+ category — something I never expected when this journey began.
But SPF was only half the story
A high SPF result was incredible, but there was another part of the testing that mattered enormously to me: UVA protection.
SPF primarily tells us about protection against UVB, particularly the wavelengths responsible for sunburn. A really good sunscreen also needs meaningful protection across UVA wavelengths.
So the next wait began: our UVA-PF testing.
And somehow, the results gave me even more to celebrate.
Our Pure Mineral Sunscreen achieved:
UVA-PF 23.69
PA++++
Critical wavelength: 377 nm
UVA/UVB ratio: approximately 0.727
UVA-PF test: PASSED
The laboratory report records a UVA-PF of 23.69, classifies the result as PA++++, and shows that it passed the laboratory’s >16 reference criterion.
Pure Mineral Sunscreen-UVAPF-Extended.pdf
PA++++ is the highest PA category, indicating a high level of UVA protection.
Then there was another number I was waiting for: critical wavelength.
This tells us about the breadth of protection across the UV spectrum rather than simply how high the protection factor is.
The benchmark we wanted to see was at least 370 nm.
Ours came back at 377 nm.
The extended instrument data are particularly reassuring because the 377 nm critical wavelength appears consistently across the individual measurements, including before and after irradiation.
And that’s the part of this journey I really want to share.
I didn’t want to simply formulate something, put “mineral sunscreen” on a jar and hope for the best.
I wanted to test it.
I wanted actual data behind what we were creating.
Our CPSR is now being updated with the sunscreen efficacy evidence, and we’ve been given the go-ahead to announce and label the product SPF 50+.
From hoping for SPF 30 to SPF 50+
There is something quite surreal about writing that.
Farmstead Naturals started because I wanted straightforward skincare for skin like mine — reactive, temperamental skin that doesn’t always get along with complicated formulas.
We’re still a small independent brand. These products aren’t being developed by some enormous multinational company.
So sending this little jar away to a laboratory and waiting for those numbers felt huge.
I would genuinely have been happy with SPF 25 or 30.
Instead, the finished formula returned an SPF test result of 64.57, followed by UVA-PF 23.69, PA++++ and a 377 nm critical wavelength.
I’m incredibly proud of it.
And perhaps the nicest part is that none of those numbers came from what I thought my formula should achieve.
They came from testing the finished product.
There have been plenty of moments running Farmstead Naturals where I’ve questioned myself, reformulated things, started again and wondered whether all the work behind the scenes would eventually pay off.
Opening these results was one of those moments where it did.
A proper tears-in-my-eyes moment. 🥹
Pure Mineral Sunscreen SPF 50+ is coming. ☀️🤎
And I honestly cannot wait to finally put SPF 50+ on that label.
Ready to try it? ☀️🤎
Our Pure Mineral Sunscreen SPF 50+ is available to shop now. Made with 15% non-nano zinc oxide and created with sensitive, reactive skin in mind.
Shop Pure Mineral Sunscreen SPF 50+ →
High protection. Minimal ingredients. Farmstead Naturals.