SPF Testing & Product Efficacy

In Australia, sunscreens are regulated as therapeutic goods under the TGA (Therapeutic Goods Administration). To launch a product, strong guidelines must be met, and while the framework sets the highest standards in the world, we believe sunscreen testing should go further.  

At Ultra Violette, we’ve put stricter standards in place: 

• Regular retesting – Until recently, we retested our products every two years. We’ve now shortened this to every 18 months. These checks are performed on products taken straight from the shelf (the same products you’re buying), so they reflect real-world conditions. We will use alternating independent labs to ensure inter-lab variability is within expected levels, which is within 20%.  
• Multiple independent SPF testing labs – every new product will be tested at a minimum of two different laboratories before launch. This helps eliminate the risk of relying on a single set of results. 
• BIPEA-audited facilities – We are working with a new and wider network of labs that have been independently audited by the non-profit organisation, BIPEA. Labs can sign up to be audited by BIPEA, who regularly send them all the same sample out to test. BIPEA then collate the results and evaluate each lab’s testing accuracy. Importantly, we are no longer working with the laboratory originally used to test Lean Screen. 
• Rest of range validated – our existing products have already been retested at BIPEA-audited labs, with results confirming SPF levels above 50 across the range.  
• In addition to the retesting results, we also hold testing to

In addition to the testing we hold to confirm the SPF labelling for each product, over the past few months we have retested the entire Ultra Violette range at multiple independent labs and consistently found SPF results over 50. The level of consistency we are seeing with the rest of the range gives us a huge level of confidence as it is at odds with what we were seeing when we started the retesting process at other labs with  Lean/Velvet Screen, where we were unable to replicate results at a level even close to SPF 50.

Additionally, none of our other products were made at the same manufacturer as Lean Screen, and because we own the IP for the large majority of our range, we have full visibility of all ingredients and their sources. This gives us confidence in the safety and performance of our products.

In Vivo Testing – On Human Skin 

The most widely used method for determining SPF is ISO 24444, an in vivo (on human skin) test.  

It might be hard to believe, but SPF isn’t determined by machines — it’s tested on real human volunteers under controlled lab conditions. A technician applies a precise amount of sunscreen to a small patch of skin on each participant’s back, alongside areas left untreated or treated with a reference sunscreen (a product with a known SPF rating). The skin is then exposed to carefully measured doses of UV light, and researchers observe how long it takes for redness (erythema) to appear. The result, called the Minimum Erythemal Dose (MED), is compared between protected and unprotected skin. From this, scientists calculate the SPF value — showing exactly how much longer the sunscreen can protect your skin from burning compared to wearing no protection at all. 

Here’s the process, step by step: 

1. Participants are recruited – volunteers must meet certain requirements to be included in the study 
2. Product application – a technician applies the sunscreen at 2 mg per cm² to a patch of skin on the participant’s back (at least 30 cm²). This area is then divided into at least 5 distinct areas or ‘subsites’ for testing. 
3. UV exposure – controlled doses of UV light are applied to the sunscreen-covered areas and to one area left unprotected with no product applied. 
4. Assessment – the next day a different technician assesses the skin for redness (erythema). The lowest UV dose that causes clear redness on each patch of skin is called the minimum erythemal dose (MED). 
5. Calculating SPF – the SPF for each participant is calculated by dividing the MED of the test product (protected skin) by the MED of the unprotected skin. 
6. Final rating – the SPF rating on packaging is the average of at least 10 participants results. 

Ultra Violette is based in Australia, where we use ISO 24444 which is the current international gold standard for SPF testing. 

 In Vitro Testing – In the Lab 

In addition to SPF testing on human skin, all Ultra Violette products are also assessed for UVA protection. This is essential for any sunscreen that claims to be broad spectrum (protecting against both UVB and UVA rays). To meet this requirement, our SKINSCREENS™ undergo ISO 24443, an in vitro (lab-based) test that doesn’t involve human participants. 

Here’s the process, step by step: 

• Application – The sunscreen is applied at a standard amount (1.2–1.3 mg per cm²) to a special plate 
• UV exposure – A spectrophotometer, which then measures how much light is absorbed vs passes through the sample.  
• Results – The process produces two key results: 
• Critical wavelength – a measure of where the area under the curve created by graphing the study hits 90%. For a product to be ‘broad spectrum’, this must be greater than 370 nm. 
• UVA Protection Factor (UVAPF) – this score must be at least one-third of the labelled SPF in order for the product to be broad spectrum.  

ISO has recently published two new SPF testing methods 23675:2024 (Double Plate Method) and 23698:2024 (HDRS).   

• ISO 23675:2024 (Double Plate Method) – a fully in vitro SPF test 
• ISO 23698:2024 (HDRS) – still uses human subjects, but without exposing them to UV until they burn 

These newer approaches are designed to be more ethical and to reduce variability in SPF testing. While not yet mandatory, they could play a big role in how sunscreens are tested in the future. These methods are permitted to be used for sunscreens in Europe but are yet to be approved by other regulatory bodies like the TGA and FDA.  

SPF results can differ between tests or labs and there’s good reason for it. SPF testing is done on human skin and every person’s skin responds differently to UV light. Several other factors can also influence results based on the lab, methodology, and technicians executing the test.  

• Small sample size – The minimum number of participants required to obtain an SPF result is 10. Compared to the hundreds of thousands of people who will end up using the sunscreen product or the population at large, this is objectively small and not representative. 
• Skin tone differences – A person’s natural melanin levels affect how quickly their skin burns. Lighter skin tends to burn faster, producing higher SPF scores, while darker skin can take longer, leading to lower scores. ISO 24444 tries to account for this by sorting participants into three skin tone bands, but only two are required for testing. Depending on which bands are included, the SPF result can be skewed higher or lower. 
• Lab choices – while ISO standards are strict, there’s still room for differences based on how the lab chooses to conduct the test. For example: 
• Some labs use a finger cot (a tiny glove for your finger) while others don’t. This can influence how evenly the product is applied 
• Labs can choose different increments for UV dosing (12%, 15%, 20%, or 25%) and how lamp output and exposure times are controlled. 
• Timing of results – It can take time for the redness to show up in the skin after exposure to UV light, which is why skin is reviewed by the technician the following day. Between the test and the review, there’s potentially a full day where something could happen to effect redness in the skin, e.g. the participant applies their favourite body lotion which calms the skin and reduces redness.  
• Technician Subjectivity – Even with ISO guidelines, technicians must interpret the skin’s reaction. Different labs or even different technicians can judge redness slightly differently, which can influence the final SPF value. 
• Control sunscreen samples – The control sunscreen sample required in the methodology is important as it can show the difference between the sunscreen being tested working, and an invalid result. The control samples, however, can be made by the testing lab themselves and do not need to be purchased from a standard store, and just like any SPF, can vary from batch to batch, potentially effecting the results.  

All of these factors help explain why SPF results aren’t always identical between labs or even between tests of the same product. It’s one reason why at Ultra Violette, we’re going above and beyond the standard requirements; by testing at multiple independent labs and auditing procedures, we make sure the SPF numbers you see on our bottles are as reliable and accurate as possible. 

In Australia, sunscreens are regulated as therapeutic goods under the TGA (Therapeutic Goods Administration). To launch a product, the following must be in place:  

1. Compliant formula – Only permitted ingredients at permitted concentrations can be used. No restricted substances, as listed in the Poison Standard, are allowed. 
2. SPF testing – The product must be tested to the Australian Standard ISO 24444:2019 and ISO 24443:2021 and ISO 16217:2020 for water resistance. The TGA only require this to be done once per product and there is no legal requirement for testing to be performed at multiple labs. 
3. Stability testing – The formula, in its final saleable packaging, is monitored for physical, chemical and microbial stability over extended periods of time under both ambient conditions and high temperatures. The TGA requires that high-temperature stability testing is completed on two batches before launch, and at least one batch must be monitored annually under ambient conditions. 
4. Labelling compliance – The packaging must meet strict rules around claims, warnings, and directions for use. 
5. Manufacturing standards – The sunscreen must be made in a TGA-licensed GMP (Good Manufacturing Practice) facility. Holding the license means the TGA has audited the facility to make sure they are manufacturing to high quality standards. You can only manufacture a sunscreen for Australia with this class of manufacturers. 
6. Quality testing – Once the product has been manufactured, it is then subjected to further quality testing to make sure it meets all the required specifications for the formula. From there, it is released onto the market.  This occurs for every batch.  

This rigorous framework ensures sunscreens sold in Australia meet some of the highest standards worldwide. 

This also satisfies regulatory requirements for the UK and Europe.

Another step we’re taking to strengthen trust in our sunscreens is introducing independent auditing of the laboratories we use. Testing quality doesn’t just come down to the method; it also depends on how carefully and consistently a lab carries out that method. 

To ensure the highest possible standard, we’re working with  Suncert, the first international organisation dedicated to sun protection certification. Suncert is recognised globally for their expertise in sun protection science, and they will be supporting Ultra Violette in two ways: 

• Auditing our labs – Suncert will help us review and assess the labs we work with, ensuring they follow ISO protocols and apply best practices in every step of the process. 
• Independent sign-off – Beyond the lab reports themselves, Suncert will act as an external expert who reviews and verifies the validity of the results before we accept them. 

With independent verification, we’re adding another layer of rigour and transparency. 

SPF testing is complex, but by partnering with the most reputable labs and experts, and going above and beyond the TGA requirements, we’re prioritising your skin and ensuring our products perform exactly as promised.