The premise, restated
Every protection factor, on every product, is determined at a fixed quantity of product per unit area of skin. Nothing about the method changes because the product is a foundation.
That single fact does all the work in this article. A figure on a make up product is not a different kind of figure, and it is not a lesser one. It is the same figure, obtained the same way, describing a product whose ordinary use departs from the test conditions more than most.
Why make up is applied thinly
The reason is not carelessness, it is design. A foundation is formulated to sit on skin without looking like a layer, to blend at the edges, to hold a finish and to avoid transferring. Every one of those requirements pushes towards a thin, worked film.
Applying a foundation at the quantity a protection factor determination uses would produce an appearance nobody wants and a product nobody would buy again. The formulation is doing what it was designed to do, and what it was designed to do is incompatible with the film thickness the figure assumes.
Because loss of protection from a thinner film is steeper than proportional, as set out in the application quantity the number assumes, the gap between the labelled figure and the delivered protection is larger here than for a product applied in bulk.
Blending, buffing and the film
There is a second effect specific to make up, distinct from quantity. Make up is worked after it is applied: blended with a sponge or brush, buffed, pressed, and then powdered or set.
Working a film redistributes it. It thins it in some places, concentrates it in others and moves it away from edges and from raised areas. Since the protection of an uneven film is pulled towards the performance of its thinnest parts, that redistribution matters independently of how much product went on.
The same applies through the day, when make up is blotted, touched, adjusted and partially removed and replaced. Each of those is a mechanical operation on the film.
| Format | Quantity applied relative to the test | Film worked after application | Reapplied |
|---|---|---|---|
| Sun protection lotion | Closest, though usually still less | No | By direction |
| Tinted moisturiser | Lower | Blended | Rarely |
| Foundation | Lower still | Blended, buffed, set | Touched up, not reapplied |
| Powder | Very low | Buffed | Sometimes |
| Lip product | Small area, small quantity | Pressed | Removed continuously by use |
Framework of this publication. It describes how published rules and guidance fit together and is not a measurement, a survey or a study.
Lip products
Lip products with a factor are a separate case and in some ways the clearest one. The surface is small, the product is applied in a small quantity by design, and it is removed continuously by eating, drinking, speaking and pressing the lips together.
The figure is obtained by the same method. Ordinary use involves near continuous partial removal, and the direction that follows, which is to reapply frequently, is more consequential here than almost anywhere else.
Layering, which does not add up
A recurring belief is that protection from separate products combines: a moisturiser with a factor under a foundation with a factor gives you the sum, or at least the higher one plus something.
It does not work that way. Protection factors are not additive, and layering two products does not produce a determinable combined figure. Each figure describes its own product at the test quantity applied alone. What a layered application actually produces depends on how the two films interact, whether the second disturbs the first, and how much of each is present, none of which has been tested.
The only defensible reading is that layering has not been measured and cannot be inferred. Where a manufacturer makes a claim about a combined routine, that claim requires evidence about the combination.
The mark, again
As with any product carrying a factor, the circled ultraviolet A mark is a separate claim. Where it is absent from a make up product, nothing has been claimed about ultraviolet A protection relative to the labelled factor.
For a product used every day of the year, that gap is worth noticing, and it is visible on the pack in a second.
The daily use argument, examined
The case usually made for sun protection built into make up is that a product used every day, delivering some protection, is better placed than a product used rarely. It is a reasonable argument and it is worth separating into its parts, because only some of it is a labelling matter.
Whether daily incidental protection is beneficial is a public health question, and it belongs to the bodies accountable for public health messaging rather than to a publication about claim language. We do not adjudicate it and we do not repeat either side's figures.
What is a labelling matter is the presentation. A product presented as delivering the protection its figure implies, in ordinary use, is making a claim about use. A product presented as containing an added factor as one element of a routine is describing itself accurately. Both can carry the same figure and the same evidence, and the difference sits entirely in how prominently and how absolutely the number is deployed.
That distinction is the whole of what this publication has to say on the subject. The figure is not the problem; treating a figure obtained under one set of conditions as a description of a different set is.
What a fair presentation would look like
Nothing in the rules requires a make up product to state that its factor assumes a quantity nobody applies. What the rules require is that claims are truthful, supported and allow a consumer to make an informed decision, and that advertising is not misleading in the impression created as a whole.
A presentation that leads with the figure, uses it as a principal selling point and implies that wearing the product delivers that level of protection is making a claim about use rather than about the product. That is the point at which a correct figure becomes a misleading communication, and it is assessed under the impression test described in sun protection claims in advertising.
Not an argument against the format
Sun protection built into a product somebody uses anyway is a reasonable thing to formulate, and it is not this publication's business to advise anybody on how to protect themselves. Guidance on that comes from the NHS, the British Association of Dermatologists and Cancer Research UK, all of whom treat sun protection products as one measure among several rather than as the whole of the answer.
The labelling point stands on its own. A number obtained under conditions that a product's own design prevents is a number that needs its conditions stated, and the conditions are not on the pack.
Powders and the setting step
Powder formats with a factor deserve a separate note, because they combine every difficulty already described and add one.
A powder is applied in a very small quantity relative to the test quantity, is buffed rather than spread, and sits on top of whatever is already on the skin rather than forming a continuous film against it. It is also, characteristically, applied to set or to reduce shine rather than to cover, which means the quantity is smaller again than for a foundation.
The determination behind the figure was made at the same fixed quantity as any other product. The gap between that and a powder pressed lightly over a finished face is the largest in the category.
Powders are sometimes presented as a solution to the reapplication problem, on the reasoning that a powder can be applied over make up during a day. Whether that reasoning holds is a question about delivered protection rather than about labelling, and it is not one we are in a position to answer with any figure.
What to take from this
Same method, same fixed quantity, a format designed to be applied thinly and then worked, blotted and adjusted. The figure is correct about the product and describes a film that ordinary use of these formats does not produce. Factors do not add across layers, and the circled mark is a separate claim worth checking.