First things first: SFF (or Sun Protection Factor) is a technical and scientific measure of the effectiveness of the sunscreen. The higher the SPF, the higher the protection on the skin from damaging UVA and UVB rays. In the simplest of terms, SPF is the amount of UV radiation required to cause sunburn on skin with the sunscreen on, as a multiple of the amount required without the sunscreen. There's a common calculation that if you're wearing SPF 30 and normally burn after 15 minutes, that the sunscreen would therefore allow you to sit in the sun for over 7 hours (30 x 15 minutes.) However, the major flaw in this is that the intensity of the sun's rays varies throughout the day, so there's no guarantee how long the SPF will remain effective; it's always better to be safe than sorry and re-apply!
So, what are the issues with the published report? You can see the details online, but essentially Which? tested the efficacy of fifteen different creams by applying small amounts to the skin in little squared sections. Studies have found that most people apply less than half of the amount required to provide the level of protection indicated on the packaging; in scientific tests six full teaspoons of sunscreen are used to test the efficiency of the SPF, so this should be the amount roughly used on a full size adult. From the accompanying video it's clear to see that the Which? scientists applied the tiniest amount of cream to the skin, way beneath the recommended amount by brands and sun campaigners to ensure effective protection. If brands are using one amount of lotion to test the level of SPF in their product and therefore base their claims, how can Which? justify not using the same quantity when seeking serious scientific answers?
The report is completely flawed. It's not clear to which degree these three sunscreens failed to match the expectations of the journalists involved, but all three brands are 100% standing by their products and reassuring consumers that their creams offer the protection they promise. Hawaiian Tropic states: "We invest considerable resource and research in product development and testing to ensure consumer safety; we guarantee the SPF claim on all products. Consumers can be confident in the efficacy and protection of all Hawaiian Tropic products, including Satin Protection SPF 30."
In my opinion, Which? have chosen to take part in a very dangerous game. Undertaking a comparison exercise between brands and finding the most pleasant to use is one thing, but undermining scientific and regulatory claims with flawed processes is completely irresponsible. Not only will this scare the public and cause the Daily Mail to go into haywire, but this report has the potential to fundamentally damage the reputation of three big brands that are doing their best to help consumers remain protected and burn free. It seems to me that Which? have cleverly launched a report into sun care when they know it will do most damage, resulting in a flood of membership sign-ups from those concerned enough to want to read the full report. (Funnily enough you can only see the whole thing if you sign up as a Which? member.)
They haven't used a responsible and recommended amount of product on the skin, so it's no surprise that some brands didn't live up to their unrealistic expectations. Furthermore, their statement that you 'can't rely on the products to provide the protection you'd expect' further takes the responsibility away from the consumer - it's up to the individual to responsibly apply and (more importantly) re-apply lotion throughout the day, especially if they sweat or spend time in water. SPF may provide the tool to protect your skin, but it's like handing a chainsaw over to a toddler and expecting the safety settings to prevent them getting hurt; it's not all about what you use, but how you use it.
In a nutshell, ignore this ridiculous and irresponsible report. Brands have to undertake rigorous testing in the sun care category, proving without doubt to regulatory bodies and foundations that their products are safe to use and provide the protection they claim. Unlike other categories (where you can make ambiguous and misleading statements, somehow managing to get away with it,) sun care is such an important topic that it's harshly regulated. Three massive brands would simply not have been able to launch ineffective products onto the market... Make of that what you will.
What do you think of the Which? report?