Ultraviolet Testing with Color Changing UV Beads
Not all sunscreen lotions are the same, as can be evidenced by a lobster-like appearance after a day of working outside. SPF 15 just didn't do the trick. Instead of using your skin as a detector of ultra-violet light (UV), try experimenting with Energy Beads or UV Beads. These indicator beads change color when exposed to UV light. It's an amazing way to test the effectiveness of sunscreen or to see if UV light is really blocked out by filters in sunglasses.
- With all of the SPF (Sun Protection Factor) numbers available, we want to know what SPF lotion really works best at keeping out the sun's harmful UV rays.
- Start by collecting various strengths of sunscreen (SPF 4, 15, and 30, for example). Since the UV Color-Changing Beads are very sensitive to changes in UV energy, you can use the beads to determine the blocking potential of the sunscreen.
- Place the beads in a zipper-lock bag and apply a layer of sunscreen to the outside of the bag.
- Use a permanent marker to write the SPF number of the sunscreen you're testing on the outside of the bag.
- Be sure to set up one bag without any sunscreen coating for comparison purposes. The bag with no sunscreen coating will serve as the control in your experiment. Expose the beads to direct sunlight for 5 minutes and look for any changes in color.
The beads will always change color, regardless of how well the sunscreen blocks UV - the beads are very sensitive! The key is to rate the color of the beads on a scale of 1-5, with 5 showing the most color or "burning" and 1 showing the least color. The bag without any sunscreen is an automatic "5." You can also test the difference between new and old sunscreen. Sunscreen manufacturers suggest that you throw away old sunscreen because it does not block out harmful UV light. Do your tests support this claim?
Place a handful of UV beads near a fluorescent light. Do any of the beads change color? Can you get a sunburn or a tan by sitting next to a fluorescent light?
"Black light" (long wave ultraviolet light) can also be used to change the color of the beads. You can purchase a black light at many specialty stores or hardware stores that have a large section of light bulbs. Steve Spangler Science also sells them. Sometimes those high intensity lights (mercury vapor) found in a gymnasium emit just enough UV light to make the beads barely change color.
Test to see if the beads change color on a cloudy day. If they change color, then you can see why doctors warn people to wear sunscreen even on a cloudy day. Observe how well the beads change color when exposed to sunlight at different times of the day. According to your data, what time of day does the sun give off its most intense UV light?
Test the ability of your sunglasses to block out ultraviolet light by covering a few beads with the lens of your sunglasses. If the beads do not change color, your sunglasses block out harmful ultraviolet light from your eyes. If not, you paid too much for that UV coating!
Test a variety of glass and plastic containers to determine which materials block out UV light. Place different transparent filters between a UV light source and the beads. Try eyeglasses and UV absorbing window film. You will find that the front windshield of most automobiles absorbs UV radiation. Usually the side windows do not have this built-in protection.
Make a UV Bead Bracelet
Thread a few beads onto a piece of leather rawhide or string to make a bracelet. Remember to stay away from any door or windows where ultra-violet light could come into the room. When you're finished, cover the bracelet with your hand and walk outside into the sunlight. Don't take your eyes off the beads as you expose them to sunlight. Like magic, the beads change from white to a rainbow of colors.
How Does It Work?
The UV Beads contain different pigments that change color when exposed to ultraviolet light from any source, including the sun. The beads are all white in visible light. In UV light, depending on the pigment added to each bead, you will see different colors. Each bead will change color about 50,000 times before the pigment will no longer respond to UV light.
The term "light" is often used as a generic word to describe many different forms of light such as incandescent light, fluorescent light, or sunlight, for instance. However, not all light is made up of the same energy. Using Energy Beads, you will be able to uncover an invisible form of light energy called ultraviolet light. None of the energy in the ultraviolet region of the light spectrum is visible to the naked eye. Just as there are many different colors of wavelengths in the visible spectrum (red, yellow, green, blue...), so are there many wavelengths of ultraviolet light.
First, there is long wave ultraviolet light (300 to 400 nanometers), which most of us recognize as "black light" - the light that is often used to make decorations glow in discos and theatrical productions. Long wave UV passes easily through plastic and glass.
Short wave ultraviolet light (100 to 300 nm) is used to kill bacteria, hasten chemical reactions (as a catalyst), and is also valuable in the identification of certain fluorescent minerals. Unlike long wave UV, the short wave UV cannot pass through ordinary glass or most plastics. The shortest wavelengths cannot even travel very far through the air before being absorbed by oxygen molecules as they are converted into ozone.
UV Beads are the perfect tool for understanding how solar radiation can be harmful and to recognize preventative measures that can be taken to reduce the risks associated with exposure to sunlight. When you expose bare skin to sunlight, your skin will either burn or tan (which doctors warn is still not healthy for your body). UV radiation wavelengths are short enough to break chemical bonds in your skin tissue and, with prolonged exposure, your skin may wrinkle or skin cancer may appear. These responses by your skin are a signal that the cells under your skin are being assaulted by UV radiation.
- These are great fun! Review by Rosie Bradley
These are a blast for the kids. I took them to the beach and had the kids make themselves bracelets with the beads. They learned that whenever they could see color in the beads, they needed to wear sunblock. No sunburns this trip! Time to order more.
(Posted on October 21, 2009)
- Wonderful Review by Barb
My frist grade students were blown away by the color changing beads! We did it as an experiment, I told the kids that something would happen when the beads were exposed to sunlight (which is what we were studying). They learned that "something" in sunlight is different from the light in our classroom. We are moving on to new activities but this was a wonderful science/art project that they could take home and share with their parents!!
(Posted on October 5, 2010)
- UV Beads in the Arctic Review by Sheila C.
Are you interested in how UV Beads react in Iceland on a glacier in the mid to later afternoon in the rain and complete overcast sky?
I bought the beads because my skin has an abnormal immune reaction (red and itchy) to UVA and I was interested in watching the beads' reaction in different situations. This was really surprising.
Seems there is no escape from UV until the sun is completely set.
Photo from January 28, 2012.
(Posted on January 31, 2012)
- Great Motivators Review by Brian Packham
I ordered these for my Science unit on Solar Energy and the students loved them. We took them out into the sun and tried different ways to protect them from the UV rays. Using Sun screen and UV sunglasses the students were surprized how they reacted. I also use them for positive reinforcement by giving each student yarn for a bracelet or necklace and give them a bead when they do the right thing in class. They love when I grab one out of the bag in class and it is white and then they get to take it outside to see what color they received. A lot of fun and great motivators.
(Posted on May 2, 2011)