Ein Mann in Woll-Kleidung am Meer in der Sonne

UV protection through wool/silk

But I was asked in my dear wool/silk group on Facebook (feel free to join the group!) to say something about the very good UV protection properties of wool/silk . All "conventional" wool/silk shops and many blogs claim that wool/silk provides excellent UV protection . But what is the truth of the claim?

Because of my own physical condition (pale skin, red tinge in my hair, phalanx of freckles on every visible spot) and a little dwarf son who is also sun-sensitive, I inevitably had to deal with the topic of sun protection a lot, so I would like to give a summary of my research.

Somehow, this research became much more detailed than I had initially thought and, above all, much more scientific than some of you might be interested in. Therefore I will first give a short summary for those who are just interested in my conclusion and then I will summarize the scientific articles on the subject. I am not a medical doctor, let alone a dermatologist - so the results here are purely my own interpretation of state of the art research and not medical advice!
In general, one has to say that the topic of sun protection with textiles is not easy and that many misconceptions are still being spread through blogs and forums. For example, I read on a blog that cotton provides the best UV protection, even though every scientific study I've read advises against using cotton as a UV protector. Others talked about how artificially added UV protection on T-shirts practically washed out - I can't confirm that either based on my research, but I can confirm that UV clothing after certain stresses (stretching or wetness) is only a tiny fraction of what it was before UV protection and then becomes pointless.

Summary recommendations

If you want to be on the safe side, then my recommendation is exactly that from the Hohenstein Research Institute - you should wear clothing that has been tested according to UV standard 801:

UV Standard 801, which assumes the most unfavorable wearing/use conditions (worst case scenario) 1

Clothing is also tested here when it is wet, when it is stretched and after several washes.
Otherwise, the unanimous opinion of all scientific texts is that although you cannot necessarily see how good the protection is from a piece of clothing, polyester and wool generally provide the best possible UV protection , whereas cotton, linen and co. fail in most cases.

Research results of the last 20 years

Interestingly enough, the idea of ​​sun protection with textiles is still quite new in the western world. Traditionally, sunscreen and/or avoidance of the sun was used here. It was only in the last 10 years that Australia began to realize that wearing the right clothing can also protect you well against harmful UV rays.
Well-known examples of effective sun protection with textiles have long been practiced, for example, by the Tuareg in Africa with their indigo-dyed lengths of fabric or the well-known saris from India, where several layers of silk are wrapped on top of each other as sun protection.
Two different sun protection concepts come into play here.
The blue coloring of the Tuareg fabric ensures that the UV factor of cotton fabric, which is actually quite bad, is improved. In principle, dark and strong colors are better than light-colored clothing, as the dye also absorbs UV rays. This is even more the case with Tuareg indigo blue than with other shades.
In the case of Indian saris, on the other hand, it is more the type of fiber that determines the UV protection. Fabrics such as linen or cotton are less suitable for UV absorption - specially treated synthetic fabrics, wool or silk are best suited, as the Hohenstein Institute has determined: ¹

Protection against UV rays is essential for natural fibers such as e.g. B. relatively low in cotton or linen. A white T-shirt only offers a UV protection factor of 10-15. The reason for this is that the cotton fibers themselves reflect or absorb little UV radiation. This is especially true if you have absorbed moisture - the fibers then become more or less transparent. [...]
Natural silk has a relatively high UV protection factor because, like modern chemical fibers, it has matting fiber components that reflect and absorb UV rays. In addition, uniform fiber structures with small gaps in the fabric or knitted fabric prevent UV radiation from reaching the skin. Depending on the color, the UPF is between 20 and 30.

At Hautsache.de you can read about the following basic rules that determine the UV protection of a textile:²

  • The type of fiber: Wool, for example, is good because the fiber has one of the highest levels of radiation absorption and therefore low UV permeability
  • The fabric weight: The heavier the fabric, the higher the protection
  • The yarns: Dense weaves are best
  • The colour: the darker and stronger the colours, the better protection
  • The surface finish: Textured is better than smooth
  • Fit: Loose-fitting clothing has better UV protection than tight clothing

In its tests, Stiftung Warentest not only criticizes the variety of labels used in test procedures, but also the UV protection in shirts declared as UV shirts - even €70 expensive cotton clothing, which was specifically advertised as having UV protection, fell in some cases tests mercilessly.

While there are "good" and "very good" marks for the UV protection of the fabric in children's hats, the results for outdoor clothing and children's T-shirts are often below average
Moisture causes cotton to swell and acts like a magnifying glass on the skin. However, it can also increase UV protection if the fabric appears darker when wet. Washing can also reduce UV protection because the fabric thins out or increase it because the stitches contract 5

But how can you determine which items of clothing are suitable for the beach and summer?

All scientific articles agree that while it is difficult to infer a garment's UV repellency just by looking at it, there are clear trends.
BMCDermatol writes:

Although it was not possible to study the parameters independently we have demonstrated the following trends. Polyester and wool fabrics usually provide sufficient UV protection (UPF 30+), while other fabrics, such as cotton, linen, and viscose, frequently offer poor UV protection. 7

(Translation: Although it is not possible to test all parameters independently, the following trends have emerged: polyester and wool usually have adequate UV protection, while other fabrics such as cotton, linen or viscose often provide poor UV protection)

The Skin Cancer Center Bochum³ points out that the use of clothing also plays a major role in UV resistance. It should be relatively self-evident that short-cut tops or bikinis do not protect against the sun's rays, but stretching clothing also reduces UV protection by a decisive amount. It is therefore recommended to wear dark, loose and airy clothing.
Gamblicher et al (2001) also found in their research "Protection against ultraviolet radiation" that merino wool in particular provides excellent UV protection.
Haerri et al (2000), Reinert et al (1997) and Hilfiker et al (1996) also showed

Natural merino wool absorbs radiation throughout the entire UV spectrum even when completely untreated.

As one English wool-silk shop correctly wrote:

This is like slathering your skin in chemical sun tan lotion - but without the chemicals.

("Wearing wool in silk is like drenching your skin in chemical sunscreen - but without the chemicals")
As Hautsache.de correctly states - there is a problem with wool:

Viscose, cotton and linen fabrics offer less protection against UV radiation
than those made of wool, silk and nylon. [...] But especially in summer we like to wear light-colored, light clothing instead of dark-green wool sweaters

Wool/silk as summer clothing

Well, we have a wonderful alternative with wool/silk (www.danischpur.de) - the fabric is light and cools in summer thanks to the silk content, making it a real alternative to cotton shirts. (And also more comfortable to wear, because you don't have a wet feeling on your body when you sweat).

On our trip through New Zealand, Australia, Thailand and South Africa, the dwarf wore wool/silk almost all the time - above all because he loves the things himself and we were happy not to have to wash them all the time, but also because they are like that even in summer are comfortable to wear and protect well against the sun.
With additional measures such as avoiding the midday sun, putting on a hat and (above all) applying lotion to our feet, we actually managed to lead Mr Käseweiß through our sabbatical absolutely sunburn-free and only very rarely had to resort to the following measures:


      1. https://www.hohenstein.de/media/pdf/328-DE_18_HOH_UVSchutz_Backgroundinfos_2011_8459.pdf
      2. https://www.hautsache.de/Die_Haut/Licht-und-Haut/Skin-protective-Beclothing-mit-Sonnenschutz.php
      3. http://www.hauttumorzentrum-bochum.de/sonnenschutz-durch-clothing textiles.html
      4. http://www.uvstandard801.com/de/uv_standard_801/uv_standard_1/uv_standard_2/uv_standard_2.html
      5. Stiftung Warentest https://www.test.de/clothing-with-UV-protection-shirt-und-hat-stands-ihm-gut-1688475-2688475/
      6. http://www.campaignforwool.co.nz/wp-content/uploads/2011/12/MERINO-FOR-MILITARY-APPLICATIONS.pdf
      7. https://bmcdermatol.biomedcentral.com/articles/10.1186/1471-5945-1-6
      8. Hilffiker, R. Kaufmann, W. Reinert et al 1996 Textile Research Jornal 66
      9. Gamblicher T et al 2001 Protection against ultraviolet radiation by commercial summer clothing, need for standardized testing and labeling, BCM Dermatology
      10. European Standard, 2002, EN 13758-1, Textiles, Solar UV protective properties, Method for testing of apparel fabrics

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