Recently found a mineral powder marketed as SPF30. Initially I thought, great, but then wondered how much I'd need to use to give me that protection. After all, there's a recommended amount of cream products people should use to acheive the SPF marketed, so surely there would be with this? There was nothing on their website to advise. So I thought I'd ask them and find out. After all, surely they would have done tests so they knew their product was SPF30, and they'd be able to tell me how they acheived that, right? Nope! Here are extracts of my email correspondence with the company (I'm happy to tell people which company it is if they PM me but don't want to get into hot water by putting it here).
Me: I asked 3 questions including, "...How much product would I need to use to achieve the SPF30?..."
Company: answered the questions except the one asking how much product to use.
Me: "...how much product is required to give SPF30? Lotion sun screens will say how many tablespoons per body/how much for certain body parts as a guide so users will apply the right amount (apparently most people don't apply enough). Having not used mineral sun protection I'm finding it hard getting an idea."
Company: "Oh yes well you will need to apply this if being exposed to the sun as a recommend time of every 30 minutes, however this will be dependent on the strength of the sun and should be used with caution when exposed to the elements".
Me: "What I meant was how much product, i.e. what weight/amount/volume would I need to put on my face, say initially, to give SPF30 coverage?"
Company: "There is no set rules for this and as long as the area has an adequate amount covered then this will be ok, so this is mainly the advice we would provide".
Me: "OK, but "an adequate amount" is subjective; it will vary from person to person. I'm asking for an objective answer so I don't inadvertently use too little of the product and put my skin at risk. Surely to market it as "SPF30" it was tested in some way, showing results that "using x amount of product over x area would give SPF30 for x amount of time"?"
Company: "Yes you are correct , this will vary from person to person depending on the skin type and tolerance, also this is tested for the sun protection factor, and is to be used mainly on the face and as long as this is covered with a good amount of the products for your own preference. I understand this is very vague, but is different from a sunscreen cream where you could be advised to apply a tablespoon amount".
And that's how it's been left. None the wiser to how they came up with the "SPF30" figure or how much I need to use!