What an SPF report actually proves — and what it does not

Six items to check before you accept an SPF test report, and the four claims that report will never cover.

Every sun-care buyer asks for an SPF report. Very few read one. The gap between a number printed on a page and a claim you can defend at a border is six specific items — and if any one of them is missing, the report is decoration.

The first line to read is the method

SPF is measured one of two ways, and the difference decides whether the number is usable.

In-vivo follows ISO 24444: ten to twenty human volunteers, 2 mg/cm² applied to the back, a xenon arc lamp standing in for the sun, and the minimal erythema dose read at 24 hours. This is the only method Saudi SFDA, UAE ESMA, the EU and the US FDA accept for an SPF value on a retail label.

In-vitro uses PMMA plates and a spectrophotometer. It is fast, cheap, and perfectly fine for screening candidates in the lab. It cannot support a label claim.

If the cover page says "in-vitro SPF" or "calculated SPF", it is a development tool, not a registration document. We see this most often from suppliers who are quoting a price rather than a product.

UVA is a separate number, and it is the one that gets missed

SPF describes UVB only. UVA needs its own evidence, and three values are worth knowing:

• UVA-PF — measured in vitro under ISO 24443, or in vivo under ISO 24442. This is the number behind a PA+ rating.
• Critical wavelength — the wavelength below which 90 percent of the absorbance sits. At 370 nm or above, the product qualifies as broad spectrum.
• Boots star rating — a ratio of UVA to UVB protection. Useful at retail, not a regulatory requirement.

The common failure is a report that shows SPF 50+ and nothing else. A sunscreen with a strong UVB filter and a weak UVA filter burns less and still photoages the skin, and Gulf regulators know it. If your report has no UVA-PF line, get one before the carton goes to print.

The report must name your formula, not a formula

A valid report carries the product name, the formula code, the batch tested, the test date, the laboratory and a named signatory. The chain from report to shipped goods has to be unbroken.

Three things break it:

• You changed the fragrance, the preservative system or the UV filter blend after testing. Any of these shifts the film on skin, and the number with it.
• The report was issued for a base formula and your version is a variant.
• The batch on the report is a lab pilot made on different equipment, not a production batch.

A minor change can often be covered by a bridging study instead of a full re-test. Ask which applies before you budget for a new panel.

Who signed it, and does the signature travel

A report from a CNAS-accredited laboratory carries weight across more than a hundred economies under the ILAC-MRA mutual recognition arrangement. In practice, SFDA, ESMA and EU competent authorities will generally accept the report itself rather than demanding local re-testing.

Mutual recognition is not automatic acceptance. Some markets still want the report translated into Arabic and attested, and some want local volunteer data behind high-SPF claims. Budget two to four weeks for translation and attestation if your agent asks for it.

Our sun-care testing runs at Jinzhi Testing, a CNAS-accredited third-party laboratory, and the report can be issued in your company's name rather than ours.

Water resistance is a separate test

"Water resistant" at 40 minutes and "very water resistant" at 80 minutes each require their own immersion-and-remeasure protocol. Neither can be inferred from an SPF report. In the Gulf this is one of the most frequently sampled claims, because pool and beach use is the entire point of the category. If you are not going to test it, do not print it.

What an SPF report never covers

• Stability. SPF decays. A formula reading 50 at release can read 42 at month eighteen. You need accelerated data at 40 °C and real-time data to confirm the value holds to the end of shelf life.
• Photostability. How much SPF survives two hours of irradiation. Avobenzone without a stabiliser fails this.
• Preservative efficacy. A separate challenge test, and the one most likely to fail on a water-based sunscreen.
• Microbiology and heavy metals. Separate panels, separate reports.

An SPF report answers exactly one question: for this formula, on this batch, measured by this method, what is the SPF. Everything else is a different document, and a supplier who implies otherwise is either confused or hoping you are.

What we hand over with a sun-care formula

• SPF in-vivo report, ISO 24444
• UVA-PF in-vitro, ISO 24443, plus critical wavelength
• Preservative challenge test
• Microbiology, five panels
• Heavy metals, mercury included
• Stability: three months accelerated at 40 °C, twelve months real time
• COA per production batch

If you already have a formula tested elsewhere and want it filled on our lines, we run a bridging protocol: same formula, same process, your existing report plus our process validation. That is usually cheaper and faster than starting the panel again, but only if the formula really is identical, which is the first thing we check.

Four questions to send your supplier today

1. Was the SPF measured in vivo, and to which standard?
2. What are the UVA-PF and the critical wavelength?
3. Which laboratory issued the report, and is it accredited?
4. Can the report be issued in my company's name?

If all four answers arrive in one message with the report attached, you are talking to a factory that does this often. If they arrive one at a time over a week, you have learned something more useful than the SPF number.