Resistance to Water
The protection provided by cosmetic products containing organic or inorganic sunscreens against sunburn is neither absolute nor permanent. One of the many factors that can affect the level of protection provided by these products is contact with water. The UV filters contained in the formulation can be leached out or physically removed by the washing action in the sea or swimming pool.
To make suncare products more effective, manufacturers have developed formulations that are more skin-friendly when immersed in water. These products have been variously labeled as water-resistant or highly water-resistant.
Various methods have been developed and published to substantiate these claims of product efficacy (water resistance), although they require the measurement of a sun protection factor (SPF) before and/or after a water immersion procedure.
days for an in vitro study with a final report
solar studies carried out
%
compliance with solar standards
Development
As part of your product development or to identify a candidate ingredient, we offer screening tests that enable you to assess UVB and UVA protection with ease.
Water resistance - In Vitro
The in vitro Water Resistance (WR) of sunscreen products was tested using the same principle as the in vivo method, which determines the percentage retention of sunscreen products by evaluating the Sun Protection Factor (SPF) before and after immersion in water. Based on a publication, this in vitro method for assessing percentage water resistance is a practical and relevant tool in terms of reproducibility and correlation with in vivo values.
Published method: Determination of the In Vitro SPF - M. Pissavini, L. Ferrero, V. Alard, U. Heinrich, H. Tronnier, D. Kockott, D. Lutz, V. Tournier, M. Zambonin and M. Meloni, Cosmetics & Toiletries, October 2003
(ref. HeWR-1)
High Water Resistance - In Vitro
The in vitro High Water Resistance (VWR) of sunscreen products was tested using the same principle as the in vivo method, which determines the percentage retention of sunscreen products by evaluating the sun protection factor (SPF) before and after several immersions in water. Based on a publication, this in vitro method for assessing the percentage of High Water Resistance is a practical and relevant tool in terms of reproducibility and correlation with in vivo values.
Published method: Determination of the In Vitro SPF - M. Pissavini, L. Ferrero, V. Alard, U. Heinrich, H. Tronnier, D. Kockott, D. Lutz, V. Tournier, M. Zambonin and M. Meloni, Cosmetics & Toiletries, October 2003
(ref. HeWR-2)
CLAIM
We can assess the sun protection of your products in full compliance with official methods, or claim the properties of your products through exclusive tests developed by WENEOS.
Water resistance - In Vivo - ISO 16217:2020 + ISO 18861:2020
This test consists of evaluating the Sun Protection Factor (SPF) and Water Resistance (WR) or High Water Resistance (VWR) by in vivo methods, before and after immersion in water of human volunteers.
This evaluation method is based on ISO 24444:2019 - Cosmetics - Sun protection test methods - In vivo determination of sun protection factor (SPF) in combination with standards - ISO 16217:2020 Cosmetics - Sun protection test methods - Water immersion procedure to determine water resistance + ISO 18861:2020 - Cosmetics - Sun protection test methods - Percentage water resistance.
This method can be used to determine :
- Static FPS (before immersion)
- SPF wet (after immersion)
- Water Resistance (40 minutes) or High Water Resistance (80 minutes)
*In vivo tests are carried out by our partners.
Water Resistance - In Vivo - FDA 2011 21 CFR Parts 201 and 310
This test consists of evaluating the Sun Protection Factor (SPF) and Water Resistance (40/80 minutes) by an in vivo method after immersion in water of human volunteers.
This evaluation method is based on FDA 2011 21 CFR Parts 201 and 310 - Labeling and Effective Testing; Sunscreen Drug Products for Over-the-Counter Human Use - Food and Drug Administration (U.S.).
This method can be used to determine :
- SPF wet (after immersion)
- Water resistance (40 minutes) or Water resistance (80 minutes)
*In vivo tests are carried out by our partners.
Control
To optimize your suncare products or check their quality, we offer you exclusive tests developed by WENEOS.
Comparison of in vitro signal absorbance measurements with resistance (batch, aging, etc.)
The statistical comparison method makes it possible to compare two sun protection products in terms of ageing, batch, benchmark, etc. When checking the absorbance spectrum between a reference and a test product using an in vitro method, two important rules must be observed. First of all, compare the two products at the same time and under the same conditions, to limit measurement variability. Secondly, a three-step verification based on absorbance values, including comparison of curve shape, variability and intensity.
In this method, a specific step for comparing the resistance of the two products can be added, such as water resistance, friction resistance, etc.
(ref. HeCOMP-2)
Published method : *In vitro comparison - A new accessible and reliable statistical method to compare the global UV protection properties of cosmetics - Lutz and S. Miksa, H&PC Sun Care, July/August 2013 | *Sunscreen products: Some practical applications for a new comparison test method to help Development and ensure Quality Controls - D. Lutz, S. Miksa and C. Guy, H&PC Today, November/December 2014
Discover the analyses additionalfor all-round sun protection
UV protection
- SPF – UVB
- UVAPF – UVA
- UVA:UVB ratio
- Photostability
- Absorbance spectrum
Beyond UV
- Ultra-Long UVA
- Blue Light
- Visible
- Infrared
- Full Spectrum
- UVC
Resistance
- Water resistance
- Sweat resistance
- Sand resistance
- Rub resistance
- Wet Skin Application
- Extreme conditions
- Persistence | Long-lasting
- Immediate protection