# Sunblock SPF

> A UK publication on the language and labelling of sun protection: what every word and number on a sunscreen is permitted to mean, who decides it, and where the gap sits between the label and what people believe. Published by Northbank Media.

## How this publication works

- Named after "sunblock", a word UK and EU guidance tells the industry not to use, because no product blocks all UV.
- No sunscreen brand or product is named anywhere on the site. There are no reviews, no rankings and no recommendations.
- No invented figures. Where a protection percentage is commonly quoted without a traceable source, the mechanism is described and the percentage is not printed.
- Every claim ruling names the instrument, code or guidance that governs the wording, and says whether it is binding or advisory.
- Clinical questions stop at the boundary and point to the NHS, a GP or a pharmacist.
- Revenue: a paid, alphabetical, labelled register of testing laboratories and regulatory consultants, never linked from an article, and one labelled newsletter sponsor line at a published rate. No affiliate links, no AdWords, no sponsored posts.

## Signature formats

- Claim ruling: a phrase as it appears on packs, its permitted status in the UK, the instrument that governs it, a compliant alternative wording, and what the phrase makes people believe that it does not mean.
- What the number assumes: the conditions under which a stated figure holds.

## Sections

### The numbers: https://www.sunblockspf.com/the-numbers
SPF, the UVA circle, the star rating and the protection categories. What each measure is a measure of, what it is not, and the conditions each one assumes.

- [What SPF is a measure of, and precisely what it is not](https://www.sunblockspf.com/the-numbers/what-spf-is-a-measure-of): SPF is a ratio between the ultraviolet dose needed to redden protected skin and the dose needed to redden the same skin unprotected, measured under a written test method at a fixed applicati
- [Why SPF and protection are not proportional, and how that gets misrepresented](https://www.sunblockspf.com/the-numbers/spf-and-protection-are-not-proportional): The factor is the reciprocal of the fraction of erythemally effective radiation reaching skin, so 30 corresponds to one thirtieth and 50 to one fiftieth. Going from 30 to 50 raises the numer
- [The UVA circle and the star rating, and why they answer different questions](https://www.sunblockspf.com/the-numbers/the-uva-circle-and-the-star-rating): The circled letters UVA indicate that a product meets a recommended minimum: ultraviolet A protection of at least a third of the labelled sun protection factor. It is a threshold, so it is e
- [The application quantity the SPF number assumes, and what changes when less is used](https://www.sunblockspf.com/the-numbers/the-application-quantity-the-number-assumes): The sun protection factor on a pack was measured with two milligrams of product applied per square centimetre of skin. That is a substantially thicker film than most people apply. Because ul
- [Broad spectrum: what the phrase requires, and where it requires nothing at all](https://www.sunblockspf.com/the-numbers/broad-spectrum-and-what-it-requires): Broad spectrum means a product protects across both the ultraviolet A and ultraviolet B ranges rather than against reddening alone. In the United States the phrase is a regulated term with a
- [Low, medium, high, very high: the categories and why labels stop at 50 plus](https://www.sunblockspf.com/the-numbers/protection-categories-and-why-labels-stop-at-50): The European Commission recommendation on sunscreen efficacy claims sets out four protection categories, low, medium, high and very high, and a recommended list of factors to be printed with

### Claim language: https://www.sunblockspf.com/claim-language
Sunblock, waterproof, all day protection, reef safe, gentle, for children. Which phrases are permitted, which carry conditions, which are ruled out, and what governs each.

- [Sunblock: why the word this publication is named after should not be on a pack](https://www.sunblockspf.com/claim-language/why-sunblock-is-a-word-you-are-told-not-to-use): Sunblock implies that a product stops ultraviolet radiation completely. No sun protection product does. The European Commission recommendation on sunscreen efficacy claims lists claims conve
- [Waterproof and sweatproof: two absolutes a sunscreen cannot claim](https://www.sunblockspf.com/claim-language/waterproof-and-sweatproof-on-a-sunscreen): Waterproof and sweatproof state that water and sweat do not affect the product. A sun protection film is reduced by immersion, by sweating and above all by towel drying, so neither absolute 
- [All day protection and once a day: claims about time that the test does not measure](https://www.sunblockspf.com/claim-language/all-day-protection-and-once-a-day-claims): The sun protection factor is determined on one film, applied at a fixed quantity, undisturbed, and read once. Nothing in the determination measures how long protection persists. Wording such
- [Dermatologically tested, hypoallergenic, non comedogenic: claims that describe a process](https://www.sunblockspf.com/claim-language/dermatologically-tested-and-other-pack-claims): Dermatologically tested says a test involving skin was carried out. It does not say what the test was, how many people took part, or what result was needed to pass. Hypoallergenic and non co
- [Reef safe, ocean friendly, biodegradable: environmental claims and their legal status](https://www.sunblockspf.com/claim-language/reef-safe-and-environmental-claims): Reef safe, ocean friendly and similar phrases have no statutory definition in the United Kingdom. They are governed by general consumer protection law and by the Competition and Markets Auth
- [For children and for sensitive skin: what those words are allowed to mean](https://www.sunblockspf.com/claim-language/childrens-and-sensitive-sunscreen-wording): There is no separate category of children's sunscreen in United Kingdom law and no defined formulation standard behind the word. What does change is the safety assessment: where a cosmetic p
- [How a sun protection advertisement can and cannot be worded](https://www.sunblockspf.com/claim-language/sun-protection-claims-in-advertising): Advertising in the United Kingdom is governed by the CAP and BCAP codes and administered by the Advertising Standards Authority. Marketing communications must not mislead, objective claims m

### Testing and standards: https://www.sunblockspf.com/testing
What an in vivo SPF test actually involves, how UVA protection is measured in vitro, the ISO standards behind the figures, and what a claim substantiation file has to hold.

- [What an in vivo SPF test actually involves](https://www.sunblockspf.com/testing/what-an-in-vivo-spf-test-involves): A sun protection factor is determined on human volunteers. A weighed quantity of product, two milligrams per square centimetre, is spread over marked areas of skin, a solar simulator deliver
- [In vitro UVA testing: how the figure behind the circled mark is produced](https://www.sunblockspf.com/testing/in-vitro-uva-testing-and-what-it-measures): Ultraviolet A protection is determined in vitro. A film of product is applied to a roughened plate at a controlled quantity, its ultraviolet transmittance is measured across the spectrum, th
- [The ISO standards behind the numbers, and what a standard actually is](https://www.sunblockspf.com/testing/the-iso-standards-behind-the-numbers): The determinations behind a sun protection label are made to international standards published by ISO: ISO 24444 for the in vivo sun protection factor and ISO 24443 for in vitro UVA photopro
- [Measurement uncertainty: what a tested figure is before it becomes an integer](https://www.sunblockspf.com/testing/measurement-uncertainty-and-a-tested-figure): A sun protection factor determination produces a mean across a panel of volunteers, with a confidence interval around it that the standard requires to reach a stated precision. That is a ran
- [Claim substantiation: what has to be held, by whom, and what adequate means](https://www.sunblockspf.com/testing/claim-substantiation-and-the-evidence-file): A claim on a cosmetic product must be supported by adequate and verifiable evidence, and that evidence forms part of the product information file held by the responsible person. Under the ad

### Regulation: https://www.sunblockspf.com/regulation
How sunscreen is regulated in the UK, who enforces the label, the European recommendation that shaped it, the responsible person, and how other jurisdictions classify the same product.

- [Sunscreen is a cosmetic in the UK, and that single fact shapes the whole label](https://www.sunblockspf.com/regulation/sunscreen-is-a-cosmetic-in-the-uk): In the United Kingdom a sun protection product is a cosmetic product, governed by the retained cosmetics regulation and enforced under the Cosmetic Products Enforcement Regulations 2013. The
- [Who enforces a sun protection label, and why more than one body has an interest](https://www.sunblockspf.com/regulation/who-enforces-a-sun-protection-label): Cosmetics enforcement in Great Britain sits with the Office for Product Safety and Standards as market surveillance authority and with local authority Trading Standards services, under the C
- [The European recommendation that shaped the label, and why it is not a law](https://www.sunblockspf.com/regulation/the-european-recommendation-behind-the-label): Commission Recommendation 2006/647/EC on the efficacy of sunscreen products and the claims made relating thereto set out the four protection categories, the recommended printed figures, the 
- [The responsible person and the product information file: the name on the pack that matters](https://www.sunblockspf.com/regulation/the-responsible-person-and-the-product-information-file): Every cosmetic product placed on the market must have a responsible person, established in the relevant market, whose name and address appear on the pack. That person holds the product infor
- [Cosmetic, drug or therapeutic good: how other jurisdictions classify the same product](https://www.sunblockspf.com/regulation/how-other-jurisdictions-classify-sunscreen): In the United Kingdom and the European Union sun protection products are cosmetics. In the United States they are over the counter drugs, with a prescribed labelling panel and defined terms.

### The pack: https://www.sunblockspf.com/the-pack
Reading a label in sequence, period after opening and expiry, heat and storage, sunscreens against products with an SPF in them, and what the symbols mean.

- [How to read a sun protection label, in order, and what each step tells you](https://www.sunblockspf.com/the-pack/how-to-read-a-sun-protection-label-in-order): Read a sun protection pack in this order: the function statement, the protection factor and its category word, the circled UVA mark, the water resistance wording and its conditions, the dire
- [Period after opening and minimum durability: two markings that measure different things](https://www.sunblockspf.com/the-pack/period-after-opening-and-expiry-dates): A cosmetic product carries either a date of minimum durability, introduced by wording such as best before end, or a period after opening shown as an open jar symbol with a number of months. 
- [Heat, storage and degradation: what the storage instruction is actually about](https://www.sunblockspf.com/the-pack/heat-storage-and-what-degrades-a-sunscreen): Sun protection products carry storage instructions because temperature affects the formulation. Elevated temperature accelerates chemical change and can destabilise an emulsion, and a separa
- [A sunscreen and a product with an SPF in it are not the same category of thing](https://www.sunblockspf.com/the-pack/a-sunscreen-versus-a-product-with-an-spf-in-it): In United Kingdom law both are cosmetic products and both may carry a factor determined by the same method. The difference is in use rather than in classification. A dedicated sun protection
- [SPF in make up and moisturiser: why the label figure rarely reflects real use](https://www.sunblockspf.com/the-pack/spf-in-make-up-and-moisturiser): A factor on a foundation, tinted moisturiser or lip product is determined by the same method at the same fixed application quantity as a factor on a sunscreen. Make up is formulated for cove
- [The symbols on a sun protection pack, and what each one actually records](https://www.sunblockspf.com/the-pack/the-symbols-on-a-sun-protection-pack): A sun protection pack typically carries several pictograms with quite different standing. The open jar with a figure is the period after opening. The hourglass points to a date of minimum du

### The gap: https://www.sunblockspf.com/the-gap
What the label states, what people hear, the vocabulary UK guidance uses, and the point at which a labelling question stops being a labelling question.

- [What the label says and what people hear: the distance this publication is about](https://www.sunblockspf.com/the-gap/what-the-label-says-and-what-people-hear): A sun protection label is precise, narrow and conditional. The reading most people take from it is broad, absolute and unconditional. The divergence is not random: at almost every element, t
- [The vocabulary of UK sun safety guidance, and the care taken over it](https://www.sunblockspf.com/the-gap/the-vocabulary-of-uk-sun-safety-guidance): United Kingdom public health guidance on sun protection is written in a vocabulary that avoids absolutes, places sunscreen alongside shade and clothing rather than in place of them, and expr
- [When a labelling question becomes a medical one, and why we stop there](https://www.sunblockspf.com/the-gap/when-a-labelling-question-becomes-a-medical-one): This publication explains what words and numbers on a sun protection label are permitted to mean. It does not answer questions about skin, risk, moles, reactions, sunburn, medication or trea

## Reference pages

- About: https://www.sunblockspf.com/about
- Editorial standards: https://www.sunblockspf.com/editorial-standards
- What we refuse to sell: https://www.sunblockspf.com/what-we-refuse-to-sell
- Register criteria and rates: https://www.sunblockspf.com/register/terms
- Newsletter and sponsorship: https://www.sunblockspf.com/newsletter