SPF Insufficient? What to Do When Test Results Cannot Be Reproduced
Short answer: It sometimes happens that a sunscreen has its claimed sun protection factor (SPF) confirmed by an accredited laboratory before it is launched on the market—only to later receive a “SPF insufficient” rating in a consumer test. This poses a real dilemma for brands and distributors: Both laboratories are certified, both operate in accordance with standards, and yet there are two different results on the table. This article provides a neutral assessment of the problem and outlines the available options for action.
The Dilemma: Two Certified Laboratories, Two Results
Imagine a product was properly tested before going on sale and labeled with the correct sun protection factor. Months later, an independent organization tests the same product again—and arrives at a significantly lower value, or in the worst case, a rating of “SPF insufficient” . So who is right?
The uncomfortable answer: Both may have followed their respective procedures correctly. The “SPF insufficient” result is not automatically proof of a poor-quality product—it can also reflect methodological variation between different, mutually recognized testing methods. This is precisely what makes the situation so difficult for distributors.
The Legal Framework: What Applies in the EU
Sunscreen products may only be advertised and sold in the EU with a specific sun protection factor (SPF) if this has been demonstrated using standardized, reproducible testing methods. This requirement stems, among other things, from Commission Recommendation 2006/647/EC on the efficacy of sunscreen products and related manufacturer claims.
The established testing standards for this are:
- ISO 24444 – In vivo determination of UVB protection (SPF). It is widely regarded as the “gold standard” for SPF verification.
- ISO 24443 – In vitro determination of UVA protection (UVA-PF).
In addition, the EU recommendation stipulates that UVA protection must be at least one-third of the claimed SPF. Anyone who has demonstrated the sun protection factor in accordance with these standards has met the legal requirements for marketing—even if a subsequent test using a different method yields a result of “insufficient SPF.”
Why Results Vary in the First Place
For several years now, the HDRS method (Hybrid Diffuse Reflectance Spectroscopy, standardized as ISO 23698) has been used alongside the traditional in-vivo method. It combines a measurement on the skin with an in-vitro transmission measurement and was developed to avoid the ethically sensitive practice of exposing the skin to UV radiation. Studies confirm that it correlates well with ISO 24444.
In theory, therefore, the methods are equivalent. In practice, however, variations can occur: Retesting a product already on the market using a different method can result in a higher—or lower—value. If the value drops significantly, the conclusion “insufficient SPF” is quickly drawn, even though the value originally determined according to ISO 24444 remains valid.
This is particularly relevant for mineral UV filters. Determining their sun protection factor is more technically challenging than for organic filters—with the result that products compliant with standards that contain mineral filters have repeatedly performed worse in such retests.
What Brands and Distributors Can Do
If your product is publicly rated as “insufficient SPF,” several steps are advisable—ideally taken simultaneously:
- Secure the data. Organize and present the original test reports in accordance with ISO 24444 and ISO 24443, along with the raw data and the safety assessment. This is your legal basis.
- Arrange for a second test. Have the product retested in an accredited laboratory—preferably according to the same standard, and if necessary, additionally using the differing method to highlight the variation.
- Communicate transparently. Objectively explain the difference between the testing methods without disparaging the other institute. Consumers appreciate clear, verifiable facts.
- Consider reformulation. Where reproducibility is a priority, switching to or supplementing the formulation with organic filters can increase measurement robustness.
- Withdrawal as an option, not an admission of guilt. Some manufacturers voluntarily remove a product from the market even though it meets legal requirements—simply because the publicly perceived test is part of their quality promise to their target audience. This is a strategic decision, not one mandated by law.
What remains important is that consumers rely on the SPF rating. A deviating test result should therefore never be ignored but always be thoroughly investigated—when in doubt, err on the side of caution.
Creating transparency: Test reports available for download—and what an SPF test really costs
An effective remedy for uncertainty is radical openness. Make your test reports publicly available for review—for example, as a download directly on the product page. This allows consumers to see for themselves that the advertised sun protection factor has been properly verified in accordance with ISO 24444 or ISO 24443.
It’s also important to provide transparency regarding the financial costs involved in determining a single protection factor. A standard-compliant SPF measurement costs, depending on the method and institute, around 3,000 to 6,000 euros—per test product and per method. Anyone wishing to validate their product using all currently discussed methods would therefore have to invest up to 18,000 euros—and even then, as described above, different results may emerge.
To make matters more complicated: Testing institutes conduct tests; they do not provide advice. They deliver a test result but offer no guidance on how to handle deviating values. The responsibility—and the full cost risk—rests solely with the distributor.
A Heavy Burden: Three Competing Measurement Methods
With the coexistence of several recognized methods, the European framework has placed a heavy burden on brands. Three competing measurement methods mean uncertainty, additional costs, and increased vulnerability for every distributor—precisely in a segment that is central to skin health. This is because UV radiation is considered the primary cause of premature skin aging; according to widespread estimates, up to 90% of visible skin aging can be attributed to it. Good sun protection is therefore not a mere accessory, but one of the most effective anti-aging products available.
This is precisely why providers of sun protection products need a high degree of resilience—technically, economically, and in terms of communication. Those who thoroughly document their data, make it openly accessible, and explain the methodological context can turn an “SPF insufficient” rating from a threat into an opportunity to demonstrate competence and transparency.
Frequently Asked Questions (FAQ)
Does “SPF insufficient” automatically mean that the product is unsafe?
No. It may be due to a methodological discrepancy between recognized testing procedures. A reputable retest provides clarity.
Can I continue to sell my product if a test yields an “insufficient SPF” result?
Legally, what matters is compliance with the relevant standards (ISO 24444/24443). A conflicting test result does not initially change this—but the reputational implications must be assessed separately.
Why does this often affect mineral filters?
Due to particle distribution, their sun protection factor is more difficult to measure consistently than that of organic filters.
What is the best first step?
Save all test reports and commission a re-test at an accredited laboratory.
Conclusion
“Insufficient SPF” is a red flag for any brand—but not necessarily a judgment on quality. As long as testing standards and methods coexist, differing results will occur. Those who thoroughly document their own data, communicate transparently, and, when in doubt, act in the interest of consumer safety will confidently navigate this dilemma—regardless of which filter principle is used in the product.
Are you interested in developing a sunscreen or launching it as a private-label product?
Sunscreen is one of the most challenging areas of cosmetic development. The formulation, UV filter system, galenics, raw material quality, manufacturing process, and packaging must all work together optimally—and ultimately, testing in accordance with standards determines which sun protection factor may actually be claimed.
Cosmacon supports you with our many years of experience in developing customized sunscreen products—from selecting and combining suitable UV filters, through formulation development and stability testing, to organizing the required SPF and UVA testing as well as the regulatory market launch. Just get in touch.
If you’d like to get started faster, Tojo Cosmetics offers ready-to-use private-label sunscreen products that can be launched under your own brand and for which the corresponding test results and product documentation are available.
For us, transparency is also an integral part of professional product development: We draw on all our experience and expertise to develop the best possible and most robust formulation for our customers. However, no reputable source can provide an absolute 100% guarantee of a specific result for every subsequent SPF measurement.
This is because sun protection remains a complex interplay of formulation, manufacturing, and testing methodology. Despite careful development and testing in accordance with standards, varying test results cannot be completely ruled out.
Our commitment at Cosmacon and Tojo Cosmetics is therefore not to promise unrealistic guarantees, but to develop sun protection products based on sound science, have them thoroughly tested, and provide our customers with expert guidance even when results do not turn out as expected.
After all, good product development is not only evident when everything works as intended—but also in how professionally one handles unexpected results.