The Very Water Resistance SPF Laboratory Test In Vivo is an advanced clinical study that determines both the Sun Protection Factor (SPF) and the ability of sunscreen products to maintain protection after prolonged immersion in water. This test provides internationally recognized data to support the labeling claim “Very Water Resistant” in compliance with ISO 24444:2019 and ISO 18861 standards.

Purpose of the Test

The purpose of this test is to evaluate the persistence of UV protection provided by a sunscreen formulation after multiple or extended water exposure cycles. It supports product claims such as SPF factors and “Very Water-resistant,” demonstrating the formulation’s durability under real-life swimming or water activity conditions.

How the Test Works

This In Vivo Apparatus Test is performed on human volunteers under controlled laboratory conditions. The study involves application of the test product on defined skin areas, followed by standardized UV exposure to determine the minimal erythema dose (MED) required to cause redness. After controlled immersion in water, the SPF test is repeated to assess any reduction in UV protection. For the very water-resistant claim, the product must maintain its SPF level after two complete 20-minute immersion cycles or an equivalent total immersion time of 40 minutes.

Testing Standards

• ISO 24444:2019 — In Vivo determination of Sun Protection Factor (SPF)
• ISO 18861 — In Vivo determination of water resistance of sunscreen products

Applications in Cosmetic Testing

• Verification of “Very Water Resistant” labeling for sunscreen and daily UV care products
• Measurement of SPF values after prolonged immersion
• Validation of product durability for outdoor and sports use
• Regulatory testing for EU, FDA, and international compliance
• Support for marketing claims such as “long-lasting protection” and “ideal for swimming or sports”

Test Procedure

1. The study is conducted under controlled environmental and light conditions according to ISO 24444:2019 and ISO 18861 protocols.
2. The test sunscreen is applied in a standardized quantity to specific areas of volunteers’ skin.
3. UV exposure is administered to determine the Minimal Erythema Dose (MED) for both protected and unprotected skin areas.
4. Volunteers undergo defined water immersion cycles — typically two 20-minute baths or longer periods as required by the protocol.
5. Post-immersion UV exposure is repeated to evaluate SPF retention and water resistance performance.

Results & Reporting

The final report includes:

• Complete protocol and testing conditions (ISO 24444:2019 + ISO 18861)
• SPF values before and after extended immersion
• Statistical analysis of SPF consistency and retention ratio
• Volunteer test data and observation summaries
• Interpretation confirming “Very Water Resistant” performance

Why This Test Matters

Consumers who engage in swimming, sports, or outdoor activities require sunscreens that maintain consistent UV protection even after long water exposure. The Very Water Resistance SPF Laboratory Test In Vivo provides objective, regulatory-compliant proof that a sunscreen maintains its protection during and after immersion, ensuring accurate product labeling and consumer safety.

Sample Requirements

• Sample size: 300 mL of finished product
• Number of volunteers: in accordance with ISO 24444:2019 (typically 10–20)
• Product type: water-resistant or very water-resistant sunscreen products
• Storage: room temperature, away from direct sunlight unless otherwise specified

Test Parameters

• Protocol: ISO 24444:2019 + ISO 18861
• Duration: 40 days (including preparation, testing, and reporting)
• Measurement: In Vivo SPF before and after extended water immersion
• Evaluation: Statistical comparison of pre- and post-immersion SPF results
• Sample quantity: 300 mL

Turnaround Time

Typical turnaround time is approximately 40 days, depending on volunteer scheduling and suitable UV testing conditions.

Deliverables

• Comprehensive laboratory report in PDF format
• SPF measurement data and water resistance analysis
• Statistical summary with ISO compliance statement
• Certification confirming “Very Water Resistant” claim validity

Compliance & Standards

The Very Water Resistance SPF Laboratory Test In Vivo is conducted in accordance with Good Clinical Practice (GCP) and fully complies with ISO 24444:2019 and ISO 18861. All procedures are performed by trained clinical specialists under controlled UV and immersion conditions to ensure reproducibility and scientific accuracy.