Sundress upf dress spf dress sun protection dress

Sundress | Redefined

Clearly, a “sundress” is intended to be worn during midday hours- hours when the sun is at its peak.  During these hours, heat may be in excess which drives us to wear something lightweight and a little exposed. Read on to learn more…



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What do you think of when you hear the word ‘sundress’?

Quite literally the term sundress refers to a dress intended to be worn while in the sun.  Most often this means lightweight, loose-fitting, and perhaps made of cotton or another textile that tends to “breathe”. In terms of skin coverage, most of the google searches for sundress our research team performed revealed styles with thin straps, sleeveless, and wider necklines. In terms of length, this ranged widely with mini to midi to maxi available.


When looking for a sundress, should we actually be looking for a "UPF dress", "SPF dress", or a "sun protection dress"?



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Why does this matter?

Clearly, a “sundress” is intended to be worn during midday hours- hours when the sun is at its peak.  During these hours, heat may be in excess which drives us to wear something lightweight and a little exposed.

Related : SPF Explained

Aside from heat, midday is also when UV is at its peak.  Remember, UV is not associated with temperature, it is invisible and does not have a temperature associated with it.  The concern is that, unless prior to wearing a sundress, efforts have been made to wear SPF / sunscreen to the exposed areas, this is also a time when UV damage can occur.

What’s wrong with the traditional definition of a sundress?

The two biggest concerns with a traditional sundress are :

  • Textiles : often cotton or linen
  • Skin coverage for chest, back and arms

Gambichler et al in Recent Results in Cancer Research that research demonstrated that ⅓ of textiles used in summer clothing have a UPF (Ultraviolet Protection Factor) of less than 15! 

This means that the material the dress is made of may not be protecting the skin effectively where covered.

The style of the sundress may also limit the amount of body surface area protected from the sun as well.

Related : SPF and UPF Learn the difference


Which textiles should be considered? 

The most common clothing textile trends for summer tend to be made of lightweight textiles including cotton, rayon, and linen.  In a study published in Dermatology  evaluating the UV transmission of summer clothing in Switzerland and Germany in 2000 by Dummer et al, over 80% of summer textiles tested were made of cotton.  According to this study, over 25% of the textiles tested under a UPF of 15, another quarter in the 15 to 25 range, another quarter in the 25-40 range, and only 25% tested over a UPF of 40.


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Cotton, depending on type and construction of the textile, is lightweight and highly breathable.  Although cotton is a commonly sought summer textile, many types of cotton can absorb sweat and holds it in the fabric. The fabric is touted to “breathe” when it's dry but when it's wet with sweat it can start to feel uncomfortable as it holds the moisture in the fabric.There are studies that show that people with eczema or atopic dermatitis favor lyocell.  It tends to cause less itching, it is softer and it can regulate temperature and moisture more effectively than cotton.

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The cotton fiber itself is inelastic with 90% made up of cellulose. The rest of the fiber is made up of pectins, proteins, sugars, and organic acids.  It is highly water absorbent and breathable. The inherent UPF of untreated cotton garments ranges from 1.6 to 13 based on a number of studies in the literature.  To increase the UPF but maintain breathability, having an additional spandex element to the composition helps.  Our studies that are supportive of our patent-pending textiles have narrowed this range of spandex to the ideal composition to achieve both sun protection and maintain breathability. 


Linen is often sought after for the summer months due to its high breathability.  From a sun protection point of view, it is very difficult to achieve higher UPF’s given the nature of the fiber and the loose composition of textiles.


I have studied bamboo with regards to sun protection as many companies tout the natural UV blocking tendency of bamboo without backing up this claim.   Bamboo is often even cited on skin cancer awareness sites for its “natural” tendency to block UV.  However, the actual measured UPF of undyed knit 100% bamboo has a UPF of 13.861 in studies I have come across.  To truly achieve sun protection the construction of the textile is key since if it is loosely knit or woven, the porosity will allow UV through. Bamboo is a natural fiber made up of cellulose, hemi-cellulose, and lignin-derived from the bamboo culm.  It is considered a bast fiber similar to jute or hemp.  Bamboo manufacturing can be either mechanical or chemical.  The mechanical process involves enzymatically breaking down bamboo and combing out its fibers but is not commonly used given its costly and labor-intensive properties. The more common process of extracting bamboo fibers is via the chemical process which is almost identical to the production of rayon utilizing carbon disulfide.


I encourage people to also consider compositions of polyester and recycled polyester for the summer simply because of its breathability and moisture-wicking properties.  As a dermatologist, I come across “sweat acne” and “yeast folliculitis” on a daily basis due to poorly chosen garments that absorb and hold sweat close to the skin. Performance polyester can achieve sun protection and moisture-wicking along with maintaining breathability.

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Why does the style matter?

I always wear a shirt outside so I just put sunscreen on my face."

I understand that this statement feels like it should make sense.  After all, all clothing can offer some protection from the sun by acting as a simple barrier to the skin.  The question really becomes, how much protection do these items really offer? 

The amount of sun protection offered by clothing really depends on the type of material and the fit of the clothing.  Sound familiar? Now that everyone has heard about face masks and how they work, this should offer a model on how clothing works as well.  With face masks, we are worried about the same issues. 

Material, effectiveness, fit, and breathability.  All 4 factors are the same factors we consider with sun protective clothing production and development.

The bigger challenge with clothing compared to face masks is that we focus on the entire body surface area- not just the nose and mouth!  

Why does this matter?  Several studies have looked at sunscreen safety and absorption of chemical sunscreen products into our bloodstream. These studies point to 4x the safe amount of chemical sunscreen products found in our bloodstream after just one day of use in recommended amounts.

Consider this. What if you took the time to consider your clothing choices.  Choose clothing that not only is made of the right textiles but also considers the fit and body surface area covered by the designs.  


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The result: Based on one of our parametric body surface area modeling studies, this could mean the potential for a close to 7x reduction in the need for sunscreen products.  If you are using almost 7x less sunscreen, it stands to reason that you will absorb substantially less as well.  There could be the potential to find that further studies show that applying sunscreen only on the exposed areas not covered by sun protective clothing could lead to the safer use of sunscreen products.

We look forward to studying this in the future. For now, we still recommend the use of physical sunscreen products containing zinc and/or titanium to minimize the risks of sunscreen use. And, of course, continue to build an understanding of the role sun-protective clothing plays in sun safety.

A special consideration... Swim

There is a special consideration when it comes to the sundress.  Consider another important activity that happens when out in the sun: taking a dip in the water!
To create a sundress that also factors in swim, a silhouette that takes into consideration both swim and sun exposure is important.  Additions such as rash guards and swim pants or capris can also factor in skin coverage while not compromising style.  

Swim dressShop now...

A flirty, fun silhouette that wears like a minidress to accommodate additions can fit the bill.  I introduced this easy fit style on QVC in the Spring of 2022.  I'm excited to continue to evolve these designs to consider the experience we have in the sun to ensure that your clothing can both protect and style!

About Dr. Erum Ilyas

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