Guires Cosmetic Science Lab
At Guires Cosmetic Science Lab, CSL formulation chemists develop broad-spectrum sunscreen products for face, body and lips, with SPF, UVA and water resistance proven to ISO 24444, ISO 24443 and ISO 16217. With more than 10 years of experience, the team develops sunscreens with elegant textures and visible-light protection that people use every day.
Start your project with Guires CSLWhat shoppers look for now
SPF is moving into daily moisturisers, primers and tinted products.
No white cast on any skin tone, and nothing greasy under makeup.
Shoppers and regulators expect SPF and UVA numbers from accredited testing.
The science
UV protection
Long-term randomised trials show daily sunscreen reduces skin cancer and visible ageing. That starts with a filter system that meets its SPF and UVA targets in every market.
Real-world use
People apply far less than the test dose, and protection drops sharply when they do. Elegant, invisible textures and visible-light protection make the real-world result closer to the label.
Key actives
Chosen for each market’s ingredient rules and your target cost. Tap an ingredient marked → to read the published evidence.
Claims & evidence
The claims brands ask for most, the study that supports each one, and how strong that evidence is.
| Claim brands ask for | Typical evidence | Evidence tier |
|---|---|---|
| “SPF 50” | ISO 24444 in-vivo | Tier 3 |
| “Broad spectrum / UVA” | ISO 24443 in-vitro | Tier 3 |
| “PA++++” | ISO 24442 | Tier 3 |
| “Water resistant” | Immersion protocol | Tier 3 |
Clinical evidence
Peer-reviewed human studies behind the actives and approaches on this page. Each links to its record.
Randomised trial · 1,621 adults · 4.5 years + 10-year follow-up
Invasive melanomas were fewer with daily use (3 vs 11; HR 0.27, 95% CI 0.08–0.97); all new primary melanomas halved (11 vs 22), borderline significant.
Green AC et al. J Clin Oncol 2011;29(3):257–263 · PMID 21135266
Community randomised factorial trial · 1,621 adults · 4.5 years
Squamous cell carcinoma tumours were 39% lower with daily sunscreen (RR 0.61, 95% CI 0.46–0.81); no effect on basal cell carcinoma.
Green A et al. Lancet 1999;354(9180):723–729 · PMID 10475183
Randomised, placebo-controlled · 588 adults aged 40+ · one summer
Fewer new solar keratoses with sunscreen (1.6 vs 2.3 per person), and more existing lesions went into remission.
Thompson SC et al. N Engl J Med 1993;329(16):1147–1151 · PMID 8377777
Randomised community trial, blinded assessment · 903 adults · 4.5 years
Daily users showed 24% less skin ageing (relative odds 0.76) than discretionary users.
Hughes MC et al. Ann Intern Med 2013;158(11):781–790 · PMID 23732711
Randomised, double-blind · 87 young adults · summer holiday
People used the same amount of sunscreen but stayed in the sun longer with SPF 30 (72.6 vs 58.2 hours), a reason to design for real use.
Autier P et al. J Natl Cancer Inst 1999;91(15):1304–1309 · PMID 10433619
In-vivo SPF study · 20 volunteers
Protection fell steeply below the 2 mg/cm² test dose, so texture that encourages generous use matters as much as the SPF number.
Faurschou A, Wulf HC. Br J Dermatol 2007;156(4):716–719 · PMID 17493070
Randomised, double-blind · 68 patients with melasma · 8 weeks
The iron-oxide formula improved melasma severity by 15% more than the UV-only sunscreen (MASI), with lower melanin on biopsy.
Castanedo-Cazares JP et al. Photodermatol Photoimmunol Photomed 2014;30(1):35–42 · PMID 24313385
Randomised comparative trial · 40 patients · 6 months
Melasma relapsed far less with the tinted, visible-light formula (median MASI rise 0.45 vs 2.43, P=.027).
Boukari F et al. J Am Acad Dermatol 2015;72(1):189–190 · PMID 25443629
Double-blind crossover · 38 people prone to cold sores
UV-triggered cold sores appeared in 71% after placebo and in none after sunscreen.
Rooney JF et al. Lancet 1991;338(8780):1419–1422 · PMID 1683420
These are published studies on ingredients, methods and routines, not on products we have made. A finished product needs its own testing before a claim goes on pack, and we design that study with you. See the full evidence library
Sunscreens are OTC drugs in the US and therapeutic goods in Australia, but cosmetics in the EU and ASEAN. Your filter choice and dossier depend on the launch list.
Concept spotlight
Example concepts to show the range. Every project starts from your own brief, and the finished formula belongs to you.
A clear gel sunscreen for all skin tones.
Iron oxides in a shade range for deeper skin tones.
Everyday lip protection with a comfortable finish.
Sectors
Stay ahead in sun protection with regulation updates, the latest research, ingredient spotlights, recalls and market trends, written by the Guires CSL formulation, testing, clinical and regulatory teams.
Explore market insights
FAQ
In accredited laboratories using ISO 24444, ISO 24443 and standard water-resistance protocols.
Sometimes, but filter lists differ and US sunscreens are OTC drugs. We often build one base with market-specific filters.
Only with substantiation, and some markets restrict the term. We review environmental wording carefully.
You do. We sign an NDA before you share your brief, and the formula and technical file are handed over at the end of the project.
Every sun protection project at Guires CSL runs inside an ISO 9001 certified quality system, with documented methods, calibrated instruments, traceable raw materials and reviewed reports, so the results behind your product can be checked and defended.
Guires CSL quality & accreditations
In their words
“Our broad-spectrum sunscreen reaches high SPF performance while spreading easily and feeling light on the skin.”
“In-vivo SPF and in-vitro UVA testing to recognised ISO methods validated our label claims and pinpointed where the formula could be strengthened.”
“UV-filter compatibility and photostability issues were resolved without compromising emulsion stability under accelerated conditions.”
“UV-filter concentrations and label wording were checked against each target market’s sunscreen rules before we submitted.”
Insights
Guidance from our formulation, testing and regulatory teams on the topics this page covers.
Building a filter system accepted in the EU, US, Australia and ASEAN.
Read articleVitamin E, vitamin C and ferulic acid are often added to sunscreens. Human evidence that they add visible benefit is limited. Here is what is known and how CSL…
Read articleIron oxides give tinted sunscreens their colour and block visible light that UV filters miss. Here is what melasma trials show and how CSL formulation scientists build…
Read articleStart a project
Our formulation chemists, testing scientists and regulatory specialists work alongside your team, from the first brief to a market-ready product. Bring a brief, a benchmark or just an idea: a scientist will reply within one working day with next steps and an indicative scope.
