We are named after a word the industry is told not to use
Sunblock. No sun protection product blocks all ultraviolet radiation, so guidance in the United Kingdom and across Europe tells manufacturers not to use the word, because it overstates what the product does. The domain is called sunblockspf.com for exactly that reason. This publication exists because the distance between what a label is permitted to say and what a reader takes from it is where almost every misunderstanding about sun protection lives.
We rule on wording and on numbers. We never name a product, never rate a brand and never tell anyone what to buy.
A number on a pack is an answer to a narrow question, asked under laboratory conditions, in a language set by regulators
SPF is a ratio, not a percentage and not a duration. The UVA circle is a pass mark, not a rating. The star system is a ratio between two protections rather than a level of one. Each figure holds only under a stated set of conditions, and the conditions are almost never printed next to the figure. We print them.
What this publication covers, and where it stops
The numbers
Every figure on a sun protection label is the answer to a question narrower than the one people ask
Open the section02Claim language
The words on a sunscreen are governed as tightly as the numbers
Open the section03Testing and standards
Behind every printed number sits a test with a written method and a stated uncertainty
Open the section04Regulation
In the United Kingdom a sunscreen is a cosmetic, and that single fact shapes the whole label
Open the section05The pack
A sun protection label can be read in a fixed order, and the order matters
Open the section06The gap
The distance between what a label is permitted to say and what a reader takes from it
Open the sectionStart here
Sunblock: why the word this publication is named after should not be on a pack
No product blocks all ultraviolet radiation. European guidance lists wording of that kind among the claims that should not be made, and the UK advertising codes treat overstated protection as misleading.
Claim languageWhat SPF is a measure of, and precisely what it is not
SPF is a ratio produced by a defined laboratory test against one specific effect of ultraviolet radiation. It is not a percentage, not a duration and not a measure of everything the sun does.
The numbersWhy SPF and protection are not proportional, and how that gets misrepresented
Doubling the number does not double the protection. The relationship is a reciprocal, the difference between high figures is small, and the way that is presented in retail and advertising is where the misleading happens.
The numbersThe application quantity the SPF number assumes, and what changes when less is used
Every printed factor was measured at two milligrams of product per square centimetre of skin. Applying less does not reduce protection in proportion. It reduces it faster, and the mechanism is worth understanding.
The numbersWaterproof and sweatproof: two absolutes a sunscreen cannot claim
Both words promise that water or sweat has no effect. Guidance treats them as claims that should not be made, and the permitted vocabulary is resistance, which is a matter of degree.
Claim languageHow to read a sun protection label, in order, and what each step tells you
A sun protection pack can be read as a sequence rather than as a picture. The order matters, because the most prominent element is not the most informative one.
The packSunscreen is a cosmetic in the UK, and that single fact shapes the whole label
Classification determines everything downstream: who assesses the product, what has to be on the pack, what evidence is required and which claims take it into a different regime.
RegulationWhat an in vivo SPF test actually involves
A panel of human volunteers, a weighed quantity of product, a solar simulator and a graded visual endpoint. The single integer on a pack is the compressed result of a long procedure.
Testing and standardsWhat the label says and what people hear: the distance this publication is about
Every element of a sun protection label has a precise meaning and a popular one, and the two are systematically different in the same direction.
The gapWe rule on claims, so we cannot take money from the people making them
No sunscreen brand can buy a listing here at any price. No product recommendations, no affiliate links, no sponsored articles. Revenue comes from a paid register of testing laboratories, regulatory consultants and claim substantiation specialists, which is business facing, alphabetical, labelled paid and never linked from an article, and from one labelled sponsor line in the newsletter, sold from a published rate card. What we refuse to sell is published in full.
The wording note
One email a fortnight on sun protection claim language: what changed in the codes, what a published ruling turned on, and one phrase examined in full. Written for people who write, approve or check labels and advertising. Unsubscribe whenever you like.
Each issue carries one clearly labelled sponsor line, sold from a published rate card that cannot influence any claim ruling. We use your address for the newsletter and nothing else. See privacy.
This page contains no commercial links. No sunscreen brand, product, laboratory, consultancy, retailer or supplier has paid for, been offered, or been promised any mention anywhere on this site, and no product is named. Every outbound link goes to a public institution or a published instrument and is marked nofollow. Published by Northbank Media.