ECOLAB Textile Care developed a sustainable washing solution for sunscreen stains

By Valentina Fontana, European Hospitality Segment Manager at ECOLAB

For many, the arrival of summer means vacation and quality time spent outdoors with family and friends. For commercial laundries, textile rental companies and hotels, the warmer summer months represent an uptick in sunscreen use and, as a result, textiles heavily soiled with sunscreen residuals.

To effectively remove the sunblock stains left behind, laundry operators face the inevitable extra costs associated with a second wash, due to the increase in product, water and energy use. Not to mention the additional time and effort.

Over the past two years the Ecolab Textile Care team has conducted thorough studies and developed a solution based on the EU Ecolabel-registered washing program OxyGuard™40  to remove these challenging stains, without compromising quality or adding to the overall cost of operations.

A little bit about sun cream

Many cosmetics and sunscreen products indicate a specific value relative to sun protection which is called SPF (Sun Protection Factor). The number defines the degree of skin protection vs non-protected skin from actinic damage, also called sun damage and especially from UVB rays which are known to cause sunburn and contribute to skin cancer risk.  It corresponds to the time that is necessary for the protected skin to develop a sunburn, if compared to a non-protected skin.

According to CE n.1223/2009 regulation dated 30 November 2009 and relative to cosmetics, the UV filters are “substances destined exclusively or mainly to protect the skin from UV radiation by absorption, reflection or scattering of the UV radiation”. Sunblock can be divided into physical and chemical type and it reduces the quantity of light radiation on the area where the sunscreen has been applied. 

Chemical sunblock contains organic molecules that can absorb and decompose UV radiation to heat, making it less harmful for our skin. Internationally the UV radiation has been classified into UVA and UVB rays, based to the length of the maximum penetration to the human skin (see picture below). According to Skin Cancer Prevention Organization (www.skincancer.org) UVA rays penetrates the skin more deeply than UVB. UVA rays play a major part in skin aging and wrinkling (photoaging), and until recently scientists believed it did not cause significant damage in areas of the epidermis (outermost skin layer) where most skin cancers occur.

Studies over the past two decades, however, show that UVA contributes to and may even initiate the development of skin cancers. On the other hand, UVB rays, the chief cause of skin reddening and sunburn, tends to damage the skin's more superficial epidermal layers.

It plays a key role in the development of skin cancer and a contributory role in tanning and photoaging. Its intensity varies by season, location, and time of day.

UV radiation and the skin. Source: https://www.skincancer.org/prevention/uva-and-uvb

Physical sunscreens reflect the sun rays; therefore, the radiation cannot reach the skin but, unlike the chemical ones, they neither keep the heat, nor penetrate the skin. They stay on the surface of the skin and therefore later on the textiles and let a very limited quantity of UV rays pass through. We can distinguish TiO2 (titanium dioxide) ZnO (zinc oxide), talc and kaolin-based sunscreens. These are all substances that allow to obtain high SPF and the protection from UVA and UVB rays. Physical sunscreens are characterized by a strong protective, covering, reflecting and scattering power. They are finely scattered and kept in suspension in the cream or a cosmetic product and therefore they are not soluble in water.

Chemistry behind the sun cream stains

Both the physical and the chemical sunscreen types contribute to the nature of stains produced on the textiles by sun protection creams. Washing a fabric stained by a cosmetic product containing sun protection substances or a sunscreen cream requires to carefully set the washing process. All the washing process parameter (pH, temperature, type of bleach, detergent, alkaline or surfactant boosters) are crucial for the control of oxidation reaction in the washing bath. It is important because oxidation reaction can activate the molecules of the sunscreen and result to a not very pleasant washing result for the laundry operators - the stained fabrics (yellow, orange or even pink) during high touristic season. The sun cream stains are often impossible or very difficult to remove and is therefore an additional cost factor for the textile service companies. Some ingredients of the sun cream are only activated by the heat and form so called proper chromophores, that are usually yellow in colour. Due to the temperature and detergents used in the washing process, the ingredient that normally absorbs UV rays and protects our skin starts to absorb visible to our eye blue light for so long, until it becomes yellow. Consequently, many ingredients of the sun creams that are white or transparent in their original state are turning into strong yellow or brownish after the washing process.

They are activated during the washing by the temperature and by the presence of the washing chemistry. In addition to this, even the smallest presence of heavy metals in the water, will activate them as well, causing the stains and resulting re-wash followed by additional water and energy consumption.

One of the most common such reactions concerns Avobenzone (INCI: Butylmethoxydibenzoylmethane). This is an ingredient used for protection from UVA rays. It is particularly unstable and even the smallest traces of metals such as zinc oxide, titanium or iron (Fe2+ or Fe3+) found in the water are enough for it to link and form the complex molecules that will not filter UV rays any longer, but dye textiles in yellow and red colours instead.

In fact, the interaction of sunscreen products with the active elements of the different washing processes is particularly complex because it is not only filters, described above, that influence the fine yellow “effect” of the textiles, but also the cream itself with its grease part. Oftentimes removal of “greasy” part from the textiles can result to a fixation of the “filter” part of the sun cream, making the entire process of washing very costly and long.

Comparison of washing process with OxyGuard40 and traditional process. Source: ECOLAB

IMAGES 1&2: view under UV light before (1) and after (2) washing with OxyGuard40 process. No stains were visible under the natural light and only two stains visible under UV light.

IMAGES 3&4: view under UV light before (3) and after (4) traditional process. All stains were visible under the natural light and almost all under the UV light

The solution

OxyGuard™40 works efficiently on sunscreen cream stains by acting on different levels – both on their grease component and on the filter part of the sunscreen – which allows for the removal of both components from the fabrics. The work conditions of the platform at a low temperature (40°C) allow to achieve outstanding results that are even better than at medium-high (50°C+) and higher temperature solutions. The fabrics appear free from yellow or pink stains and show excellent levels of whiteness together with a superior softness. The time of washing cycles does not increase, if compared to the conventional process and it is not necessary to add additional surfactant or solvent boosters.

OxyGuard™40 offers an innovative and sustainable solution for the removal of sunscreen cream stains by washing at low temperatures (starting from 40°C) and is EU-Ecolabel certified.