Why this article exists first
This publication is called Sunblock SPF and sits on a domain of that name. That is deliberate, and it needs explaining rather than excusing.
Sunblock is a word the industry has been told not to use. It survives in ordinary speech, in the way people search, and in the vocabulary of a generation who grew up with it printed on packs. The gap between a word people still use and a word the label is no longer permitted to carry is exactly the subject of this publication, so putting it on the masthead is the shortest way of stating what we are about.
What follows is the ruling on the word, in the format used throughout this site.
What is wrong with the word
The objection is not stylistic. It is that the word describes a mechanism the product does not have.
To block is a binary. A blocked pipe carries nothing; a blocked road admits no traffic. Applied to radiation, blocking means none passes. A sun protection product attenuates: it absorbs and scatters a proportion of incident ultraviolet radiation and allows the rest through. That is what the sun protection factor measures, and the measurement is expressed as a ratio precisely because the quantity getting through is not zero.
Under the definition of the factor, a product labelled 30 lets one thirtieth of the erythemally effective radiation through under test conditions, and a product labelled 50 lets one fiftieth through. Small fractions, but not none. A word implying none is describing a product that does not exist, and the arithmetic behind that is set out in what SPF is a measure of.
What actually governs it
Three layers do the work, and they are worth separating because they have different force.
The European Commission recommendation on sunscreen efficacy claims. This is the document that named the problem. It sets out that sunscreen products should not carry claims implying total protection, and lists example wording of that character. It is a recommendation rather than a regulation, so it does not create a binding obligation by itself. Its practical authority comes from being the reference point that industry, testing houses and enforcement bodies all work to.
The common criteria for cosmetic claims. Retained in United Kingdom law, these require among other things that a claim about a cosmetic product is truthful, that it is supported by adequate and verifiable evidence, and that it allows a consumer to make an informed decision. A claim of complete blocking cannot be supported, because no test produces that result.
The United Kingdom advertising codes. Administered by the Advertising Standards Authority and written by the Committee of Advertising Practice, these require that advertising is not misleading and that objective claims are capable of substantiation. They apply to packaging where the packaging is used in advertising, and to every retail listing, advertisement and social post.
Together these mean that a business using the word would need to explain how a term denoting complete blocking is truthful, supported and not misleading. There is no available answer.
| Wording | The problem with it | What it would need to be true |
|---|---|---|
| Sunblock | Implies complete blocking | A product transmitting no ultraviolet radiation |
| Sunblocker | Same claim, agent noun | The same, and it does not exist |
| Total protection | Explicit completeness | A protection factor without an upper limit |
| 100% protection | Quantified completeness | Zero transmission, which no test reports |
| Blocks harmful UV | Completeness plus an undefined category | A filter that distinguishes harmful from harmless radiation |
| Physical blocker | Completeness plus a simplified mechanism | A filter that reflects all incident ultraviolet |
Framework of this publication. It describes how published rules and guidance fit together and is not a measurement, a survey or a study.
Where the word survives
Removing a word from packs does not remove it from language, and the persistence of sunblock is one of the clearest demonstrations of the gap this publication is about.
It survives in speech, because people learned it before it was discouraged and because it is more descriptive of what they want than sunscreen is. It survives in search, because people type what they say. It survives in retail listings written by third parties who are not looking at a regulatory guidance document. It survives in older stock, in imported products marketed under other rules, and in translated copy. And it survives in domain names, of which this is one.
None of that makes the word acceptable on a pack. All of it makes the word interesting, because the thing that gives it staying power is exactly the thing that makes it a prohibited claim: it promises completeness, and completeness is what people want.
Sunblocker, total block and the family of near misses
The same reasoning covers a family of related wordings. Sunblocker, total sunblock, complete protection, total protection, blocks all UV rays and one hundred per cent protection are all forms of the same claim, and none of them is rescued by rewording.
Two variants deserve separate attention because they are subtler.
Blocks harmful UV rays. The qualifier does not fix the problem. It restates the same completeness claim about a subset, and it introduces a second difficulty, because harmful is not a defined category of radiation and the wording implies the product distinguishes between harmful and harmless ultraviolet in a way that no filter does.
Physical blocker. This is trade vocabulary describing a class of ultraviolet filter by its supposed mode of action. Used internally it is imprecise but harmless. Printed on a consumer pack it carries the same implication of complete blocking, and it has the additional problem that the mechanism it implies, purely reflecting rather than absorbing radiation, is a simplification of how those filters behave.
The claim to which all of these are compared is the one the label is designed for: a stated factor, a category word, and the circled ultraviolet A mark. That combination says what a product does without asserting anything it does not.
Why the word will not go away
Vocabulary is not removed from a language by regulation. It is removed by disuse, and disuse takes a generation. The word sunblock was in ordinary British use for long enough to be learned by people who are now buying products for their own children, and the word they learned is the word they will type into a search box.
This produces a persistent mismatch that anyone working in the category runs into. Consumer language and label language have separated, and they have separated specifically at the point where the consumer language is more optimistic than the product is. That is not an accident of history. The word that survives is the one that describes what people want the product to do.
The practical consequence for a business is uncomfortable and worth stating. The vocabulary customers use to look for a product is vocabulary the product may not use to describe itself. There is a real difference between describing a product and describing what customers call a category, and the boundary is not always obvious. Where the word appears in a search campaign, a page title, an article or a domain, the question is whether it is functioning as a description of what this product does. That is a question for a business and its advisers rather than one this publication answers.
What we can say is that the survival of the word is the best available evidence for the argument this publication makes. A discouraged term outlives its prohibition because it says what people hoped was true. Everything else on the label is an attempt to say something more accurate in a way that will actually be read.
If you have the word in your copy
The replacement is not a synonym, because the point is that the meaning is wrong rather than the register. What replaces it is a description of what the product does.
Wording along the lines of protects against ultraviolet A and ultraviolet B radiation, or filters ultraviolet radiation, states the mechanism correctly. Wording that states the factor and the protection category states the level correctly. Neither promises completeness, and neither needs to, because a very high protection factor is a strong claim already.
Where the word appears in a domain, a legacy brand element or an existing search campaign, the position is less simple, and the question becomes whether the use is a claim in the relevant sense or a name. That is a matter for the business and its advisers. What is not in doubt is that using it as a description of the product's performance is a claim, and one that cannot be substantiated.
What to take from this
Sunblock describes a mechanism no sun protection product has. Guidance lists that character of claim among those that should not be made, the common criteria require claims to be truthful and supported, and the advertising codes require that objective claims are not misleading. The word persists because completeness is what people want, and the distance between what they want and what a label may promise is where this publication lives.