Science to Live By: Sunscreen Science, Sunblock Art

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© J. Dirk Nies, Ph.D.

Summertime, and a sunburn is easy.

Sun is shinin’ and the UV is high.

(With apologies to Edwin DuBose Heyward and George Gerswhin.)

Sunscreen Science

Piz Buin is a mountain high in the Alps situated on the border between Austria and Switzerland. Its 10,866-foot summit can be ascended from either the north or south via glaciers and open stretches of relatively easy climbing. Franz Greiter, a young, Tyrolean, chemistry student, suffered a severe sunburn in the bright sunshine, thin alpine air, and highly reflective snow while climbing Piz Buin in 1938.

Inspired by this painful experience and his love of the outdoors, he went to work in a small room in his home formulating creams effective as sunscreens. Greiter soon developed what was to become the world’s first commercially viable sun protection product. Named Gletscher Crème (Glacier Cream), this product became the basis for Piz Buin, the company named in honor of the mountain and his epic sunburn there.

I used Piz Buin® (as it was called) in the high country of the Colorado Rockies in the 1960s. I remember it as a thick, greasy, poorly homogenized cream with a funny yellow-orange-brown color and a distinctive, peculiar smell. Nevertheless, it was highly sought after by mountaineers and avid skiers, and as a kid, I wore it almost like a badge of honor and camaraderie.

Franz Greiter desired a way to quantify the effectiveness of his products, and those of his competitors. For this purpose, he developed the concept of SPF, the Sun Protection Factor, which has become the industry standard for measuring the effectiveness of sunscreens.

The SPF rating tells how well a sunscreen blocks the burning ultraviolet (UV) rays of sunlight when applied at an even rate of 2 milligrams per square centimeter of skin area. For example, when swimming or sunbathing, applying 30 g (1 oz) an SPF 30 sunscreen evenly over exposed surfaces of your body allows you to stay in the sun 30 times longer.  In other words, if your bare skin normally sunburns in 20 minutes, when you use a sunscreen with an SPF of 30 you will sunburn in 600 minutes (10 hours) because only 1/30 of the burning UV rays reach your skin.

Much progress has been made in the efficacy of sunscreens. The original Gletscher Crème sunscreen had an SPF of only 2. Today we can purchase sunscreens with an SPF of 50 or more. The theoretical duration of protection afforded by these products rarely is achieved in practice however.  Sunscreens must be reapplied, usually every two hours, to work well.

In addition to the array of sunscreen creams, oils, lotions and sprays that are available, sun protective fabrics are being developed and marketed using novel weaves, greater thread counts per inch, and fabrics pre-treated with UV-inhibiting ingredients during manufacture. Like sunscreens, fabrics have their own rating scale, the ultraviolet protection factor (UPF).

Summer hats and clothing made from conventional fabrics have a UPF in the range 3 to 6. Apparel made with UV protective fabrics afford a UPF as high as 50. Fabric sprays are available that can raise the UPF of conventional summer clothing to 30 or more, as well.

Sunblock Art

As a child, Binh Danh was intrigued by images left on the lawn by a discarded rake or an infrequently used garden hose.  These observations inspired Danh to merge biological science and photography to invent a new art form, a chlorophyll printing process, in which photographic images are embedded within leaves.

To create these organic pictures, Danh first makes a negative image of a photograph in a transparent material. This image-bearing transparency then is placed on a leaf and secured with a pane of glass on top and a solid backing underneath. The dark portions of the negative act as a sunblock, inhibiting both photosynthesis and the bleaching effects of sunlight on the leaf’s natural pigments.  Within hours or days (when the process works), the image from the negative is incorporated within the leaf.

Danh was born in Viet Nam. At a very young age, he and his parents immigrated to California. The Viet Nam war is “not talked about in the family because it’s so painful.” “People in the United States wanted to forget because it was a war that Americans didn’t win. But for my parents’ generation it was a war they lost.”

To revive memory, explore justice, and process trauma, loss and death from war in an artistic way, Danh transferred iconic Vietnam War images onto leaves of tropical plants and grasses, an artistic medium that serves as a reminder of the landscape of his erstwhile country. To preserve the images, the plant materials are encased within blocks of resin.

Haunting and evocative, poignant and thought-provoking, his work has been displayed in universities, museums, and galleries. Here in Virginia, Danh has served as the Frances Niederer Artist-in-Residence at Hollins University and the Copenhaver Scholar-in-Residence at Roanoke College. Now an assistant professor of photography at Arizona State University, his artwork has brought him global recognition.

In these two lives – one a scientist, the other an artist – similarly interwoven with passion, pain, observation, creativity and hope, the world has been changed a little bit for the better.

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