Kids, Halloween is the perfect time of year to try out spooky mad scientist projects. With some laundry detergent you can make a glow-in-the dark skull that you can put on your sidewalk or window that will be invisible during the day but will glow at night.
Materials
- liquid laundry detergent or powdered detergent mixed with a little water
- sponge or paper towel
- if you need help drawing a skull then find a stencil (see link below)
- thick paper
- black light
Please note: All chemicals and experiments can entail an element of risk, and no experiments should be performed without proper adult supervision.
Make the Decoration
- Cut out the shape of a large printed skull on a piece of thick paper and then cut out the eyes, nose, and mouth.
- Dampen a sponge or paper towel with the liquid laundry detergent. You want it wet enough to deposit the color, but not dripping wet.
- Blot the paper with the detergent-coated sponge to fill in the shapes of the skull.
- Hang the skull with the wet side out. Shine the black light onto the skull when you want to see it. Turn the light off when you don't want to see it.
- This project works well using a sidewalk, wall, or windowpane instead of paper. In this case you’ll use a cut-out as a stencil. If you ‘paint’ on your porch you can switch out the normal light bulb with a black light bulb. Or you can use a black light on an extension cord and put the decoration anywhere. Wash away the picture when Halloween is over.
How It Works
Laundry detergents contain brightening agents that glow when exposed to light, especially ultraviolet light like in sunlight or under fluorescent lights. When you shine a black light on detergent you get a very bright glow. The glow is bright enough that you don't need total darkness to get a nice effect. One of the most common classes of molecules with this property is the stilbenes (see below for more information) which absorb energy in the UV portion of the spectrum and re-emit it in the blue portion of the visible spectrum.
Stilbene: diarylethene, a hydrocarbon consisting of a cis-ethane double bond with a phenyl group on both carbon atoms; derived from the Greek word stilbos which means shining.
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Kathleen Carrado Gregar, PhD, Argonne National Labs
[email protected]
October 2011
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References: http://chemistry.about.com/od/halloweenchemistry/a/glowingskull.htm (a link to the stencil can be found here, too)
http://en.wikipedia.org/wiki/Optical_brightener
For more Halloween Science projects check out:
http://chemistry.about.com/od/halloweenchemistry/a/halloweensci.htm
