We sent a batch of sunscreen off to Eurofins/Dermatest in Australia who are the main sunscreen testing lab for NZ and Australia. The testing includes an In Vitro test for Broad Spectrum protection and an In Vivo test on 10 people for SPF.
The Bad News: We can only claim SPF 25 at present although our actual test result was 28.1, so we'll need to change our labels, bugger!
The Good News: while SPF 30 protects from 96.7% (about 97 out of 100 photons are blocked), SPF 25 blocks 96 out of 100 photons. It's not a linear scale or representative of how many extra hours you can stay in the sun.
The confusion and dilemmas: The test results for SPF on 10 people varied between 25 and 35, our actual average was 28.1 but we can't say that on our labels, we have to say SPF25. We could adjust the recipe and try for SPF 30 but this would require a fresh set of tests and several thousand dollars more. So for this year we will stick with SPF25.
SPF or Sun Protection Factor is the measure of how much solar energy is required to produce sunburn on protected skin relative to unprotected skin. Broad Spectrum offers protection from both Ultra Violet A and B rays. If you want to check out our test results they are available here.
This has been one of the most challenging recipes we've worked on. After much research and deliberation, we are using a product called Zinclear as the foundation. This is a dispersion of Zinc Oxide nano particles in the Coco Caprylate/Caprate which are all naturally occuring ingredients, and have ECO Cert, and Natural Products certification. We are very happy with the final product, and have had great feedback from all our volunteers. For more information please check out: https://millstreamgardens.wordpress.com/2015/10/08/our-sunscreen/
Apply to your skin before venturing into the sun. Re-apply regularly. Unlike the old style zinc sunscreens, ours won't leave your skin looking white. Common Sense: Avoid exposure during hottest part of day, wear light clothing and a hat.
Zinc Oxide is a broad spectrum UV blocker, and works instantly, the cream base and plant extracts enhance the SPF and help protect your skin from sun damage.
Made with: Infusion of Green and Black Tea in Water, Zinc Oxide (nano) and Coco Caprylate/Caprate*, maceration of Comfrey, Aloe vera and Elderflower in Sunflower Oil, Cetearyl and Sorbitan Olivate (emulsifier)*, Lanolin, Beeswax, Essential Oils of Tulsi and Carrot Seed, Naturaguard Ultra*, Bicarbonate of Soda. * ECO certified ingredients.