LED emission spectra

A student gave me a decoration that contains red, green, and blue LEDs that light up apparently randomly alone and together.  I used an Ocean Optics USB2000 spectrometer with a fiber optic sensor to study the glow.  The Overture software that I used has this cute feature that overlays colors on the visble light spectra.  The emissions from each color of LED (red ~650 nm, green ~515 nm, and blue ~465nm) are quite clear in these spectra.

The Pie in Pyrex

I was reading an article in the Fall2012/Winter2013 issue of "Chemical Heritage" (R. Blaszczyk, Cooking with Glass) about Pyrex bakeware.  Apparently when Corning developed borosilicate ovenware, the first dish produced was a pie plate.  The names considered for the glass were thus Pie-Rite or Py-Right, but then it was changed to Pyrex in 1915 (to rhyme with Nonex, another brand of Corning glass).  Seems appropriate to mention pie on Thanksgiving!  Hope yours is good.

Starch-containing packing peanuts

Adding water to starch-based packing peanuts begins to dissolve them (conventional polystyrene peanuts are not soluble in water).  If just a LITLLE water is added to the peanuts, only their edges dissolve and they beome sticky.  The sticky peanuts can be then stacked into larger structures.  Colored versions of these sorts of packing peanuts are marketed as "Nuudles".  This demonstration illustrates concepts of like dissolves like, solvent welding, and recyclability of these starch-containing polymers.

Hydrogen Balloon Fail

I was doing a demo show yesterday, and when my helper attempted to detonate a balloon containing hydrogen and oxygen gas with a lit candle on a stick, the ballon simply popped rather than detonating.  This has happened a handful of time, typically with pure hydrogen in the balloons rather than a hydrogen-oxygen mix.  What I think is happening is that when the candle flame approaches the balloon too slowly, its heat weakens the balloon and causes it to fail.  The gases are then released in such a way that they do not detonate in contact with the frame.

Fake Frost and Window Crystals

Saw this fake frost on the store windows at a Bass Pro Shop today.  I do not know how it was made, but it shows pretty crystal patterns.  For comparison, the van windows have real frost.  One can saturate water with Epsom salt (magnesium sulfate) and paint the solution on dark-colored paper.  When the water on the paper dries, the white salt crystals look like frost. When I was a graduate student some twenty years ago, I would occasionally work with organic compounds that melted at temperatures not far above room temperature.  Sometimes a flask with a film of this melted liquid would cool in my hands.  As the film solidified, pretty crystal stars would form along the walls of the flask.  This was always fun to see.  Update on 6-4-13:  today one of my kids got some Crayola Crystal Effects Window Markers.  When the marker ink dries it makes pretty crystal stars.

National Chemistry Week 2012

The theme for this year's 25th Annual National Chemistry Week (October 21-27, 2012) is nanotechnology.  In the spirit of that I set up a display at Bradley University about nanotechnology and a ruler next to a sign saying "How tall are you in nanometers?"  The idea is adapted from a display that I saw at the University of Texas-Austin last year.

Analogy for Brownian motion

I was feeding a potato chip to a pool full of small fish and I noticed that as the little fish surrounded the chip and nibbled at it, the chip moved around randomly.  I thought this was sort of an analogy for Brownian motion, where collisions between solvent molecules and small suspended particles causes the particles to move around in a random fashion.

Cover picture

The October, 2012, issue of the Journal of Chemical Eduation came out recently. I have two papers in it: one from work done at Bradley University "Take-Home Nanochemistry: Fabrication of a Gold- or Silver-Containing Window Cling", and the other from work at the University of Texas "New Nanotech from an Ancient Material: Chemistry Demonstrations involving Carbon-based Soot". A picture from the soot research was used for the cover.

Thermal Conductivity Demo

Saw this thermal conductivity demo at the old Lakeview Museum in Peoria yesterday.

Neil Armstrong's Passing

Just heard that Neil Armstrong passed away this past weekend. I was born about a month after his trip to the moon. Anybody who rides a rocket the size of the Saturn V has my respect - demos with small rockets are crazy enough. The picture was taken late last year at the Houston Space Center - very cool.

Beer Fluorescence

 

Many carbon-containing materials fluoresce.  Green laser pointers (e.g., 532 nm) can produce yellow or orange fluorescence and violet laser pointers (e.g., 405 nm) can produce whitish fluorescence. Here lasers cause beer to fluoresce in a colorless glass bottle.

Gold Ruby Glass

Gold ruby glass (also known as cranberry glass) obtians its stunning red color from its structure at the nanoscale level.  "Nanoscale" refers to the size scale range typically between 1-100 nanometers.  A nanometer is very small (the prefix "nano" comes from the Greek word for dwarf) - it takes a billion nanometers to make a meter.  For centuries, people have added gold compounds to glass, producing nanoscale gold metal particles - nanoparticles.  These gold particles have the ability to absorb greenish light in a phenomenon called plasmon resonance.  When white light, comprised of all colors, has greenish colors removed by the gold nanoparticles, the resulting light reaching the eyes appears red. 

The photo was taken of a gold ruby glass collection at Bradley University (http://www.bradley.edu/about/publications/hilltopics/2012spring/lydia/). 
Visible light spectroscopy was done on one of the plates (see: http://www.bradley.edu/inthespotlight/story/?id=96b71938-ee8a-4615-a06d-d04080208b2b).  The spectrum is shown below:

A method for using gold compounds to produce gold nanoparticles in transparent silicone and give that spectacular gold ruby color can be found in D. J. Campbell, R. B. Villarreal, T. J. Fitzjarrald, “Take-Home Nanochemistry: Fabrication of a Gold- or Silver-Containing Window Cling” J. Chem. Educ., http://dx.doi.org/10.1021/ed200466k.

Sulfur in Illinois Coal

Illinois coal tends to have a bit of sulfur in it.  Unfortunately, that makes it difficult to use as fuel for power plants, because it produces sulfur oxides, which in turn combines with water to produce acid rain.  A story of how sulfur in coal damaged cars and clothes in Peoria, IL, is described in

D. J. Campbell, E. A. Wright, M. O. Dayisi, M. R. Hoehn, B. F. Kennedy, B. M. Maxfield, “Classroom Illustrations of Acidic Air Pollution Using Nylon Fabric”, J. Chem. Educ., 2011, 88, 387-391.  The pictures show yellowish elemental sulfur and white crystalline sulfate salts on bituminous coal exposures near Bartonville, IL.

Finally found The Metric Marvels

For several years I have mentioned to people, including students in my classes, about cartoons that I saw as a little kid that were like School House Rock only they introduced me to the metric system.  There was a Meterman (in the cartoon I learned that a millimeter was about the thickness of a dime and that a meter was a little longer than a yard) and there was a Wondergram (in the cartoon I learned that a gram was about the weight of a paper clip).  Try as I might, I could not find out about these cartoons.  I was beginning to think I had imagined the whole thing.  Well, tonight I finally stumbled across information about them - they were called The Metric Marvels and more details can be found here:  http://www.thefullwiki.org/The_Metric_Marvels.  A black and white introductory clip can be seen here: http://www.youtube.com/watch?v=eW98QCk2FdA.

Bubble Snouts

OK, not sure this is a demo so much as just a cool thing to do with bubbles. Simply use a rubber band to stretch terrycloth fabric over the wide part of a funnel made from the top of a 1 liter soda bottle.  Dip the fabric into bubble solution and blow into the narrow part of the funnel (do not inhale!).  The air pushes through the terrycloth to produce a stream or snout of many small bubbles. 

Geology Demo - Seltzer Popper Volcanoes

These demonstrations are a twist on the classic homemade volcano, in which vinegar and baking soda chemically react in a model of a volcano to produce sodium acetate, water, and carbon dioxide gas. The carbon dioxide bubbles up out of the model to produce bubbling “lava” which oozes out of the “volcano”.  The picture below shows the same reaction in a soda bottle (food coloring and dish soap have been added to make the lava flow more impressive).

But what about the volcanoes with more explosive eruptions?  Here we adapt another classic demonstration involving film canisters and Alka-Seltzer tablets. Wear eye protection.  First lay down a sheet of plastic to make cleanup easier. Place a film canister into a clay volcano, setting the lid aside for now.  Fill a milk cap with glitter. Fill the film canister halfway with water, with maybe a little dish soap and red and yellow food coloring for a “lava” effect.   Break a tablet of Alka-Seltzer in half (any more that is wasted).  Make sure everything is ready and the area is cleared out around the volcano.   

Then, QUICKLY add the half-tablet of Alka-Seltzer to the film canister, cover the canister tightly with the lid, place the milk cap full of glitter on top of the lid, and take a step back (NEVER stand over the lid).  The citric acid and baking soda in the tablet dissolve in the water and chemically react to produce sodium citrate, water, and carbon dioxide gas. The gas pressure builds up in the capped film canister until the lid pops off, scattering the glitter and sending reddish suds oozing down the side of the volcano. 

   
We can also use the Alka-Seltzer tablets to illustrate the effects that size has on processes.  If the half-tablet that is added to the film canister is first broken into small pieces, it will dissolve much more quickly in water to react and produce carbon dioxide gas.  The result is that, with all else equal, a popper volcano with the broken-up half-tablet will pop more quickly after loading than one with an intact half-tablet.  This illustrates how processes can proceed more quickly at smaller scales.  For example, many people are studying how making things really small (at the nanoscale) with lots of surface area can speed up chemical reactions.  

Another note:  We have also noticed that a film canister fits into the top of a milk jug with just a little widening (we also colored the jug piece with permanent markers).  This seems to be very inexpensive way to make a waterproof volcano cone without having to use modeling clay. 

Reference: Johnsen, N. V.  Nano Effervescence.  http://www.exo.net/~jillj/activities/nanoeffervescence.pdf (accessed January, 2012).

Geology Demo - Liquid Nitrogen Base Surge and Downburst

CAUTION: Liquid nitrogen is very cold and presents a serious frostbite hazard, especially if it gets trapped against your skin (e.g.in your clothing). Additionally, gaseous nitrogen occupies more volume than the same quantity of liquid nitrogen. Gaseous nitrogen produced quickly enough in sufficient quantities can displace oxygen from the air. Containers filled with liquid nitrogen could fail without warning due to thermal shock or gas pressure. Protect yourself accordingly.

Base surges and downbursts occur when dense gases sink rapidly down through less dense gases and spread outward upon impacting the ground. Base surges are clouds of gas and dust that move along the ground away from a volcanic eruption or a nuclear explosion. It is often produced when a column of these clouds collapses to the ground. Downbursts, and smaller microbursts, occur when cold air sinks to the ground from a thunderstorm. A similar phenomenon seems to occur during the filling of a typical 4 liter Dewar flask with a relatively narrow neck from a liquid nitrogen supply line. As the liquid nitrogen (boiling at 77 K) first passes through the supply line and into the flask at room temperature (about 298 K), the liquid nitrogen flashes into pressurized vapor. The vapor rushes out of the Dewar flask, creating a column of cool nitrogen vapor and condensed water droplets. As the supply line cools, liquid nitrogen actually makes it into the Dewar flask. The liquid nitrogen boils away less rapidly and the pressure forcing the nitrogen vapor up from the Dewar flask decreases. The cold dense vapor column then collapses down and spreads across the ground, resembling a base surge or a downburst.

References:

Clark Johnson. Base Surge. http://www.geology.wisc.edu/~g111/Terms/base_surge/base_surge.htm (accessed June, 2006).

Denton County, Texas. Downbursts. http://www.co.denton.tx.us/dept/main.asp?Parent=82&Link=84#Mistaken (accessed June, 2006).

BELOW: A liquid nitrogen base surge: (FIRST) Formation of the column of cool nitrogen vapor and condensed water and (MIDDLE) collapse of the column.  (LAST) Surge of air moving out from a thunderstorm rain column near Carlsbad, NM, in June, 2012.

Geology Demo - Liquid Nitrogen Geyser

CAUTION: Liquid nitrogen is very cold and presents a serious frostbite hazard, especially if it gets trapped against your skin (e.g.in your clothing). Additionally, gaseous nitrogen occupies more volume than the same quantity of liquid nitrogen. Gaseous nitrogen produced quickly enough in sufficient quantities can displace oxygen from the air. Containers filled with liquid nitrogen could fail without warning due to thermal shock or gas pressure. Protect yourself accordingly.

 

A geyser is a steam and water eruption (spring) water coming into contact with a very intense underground heat source. Certain geysers are periodic, but most of them occur in periods that vary from seconds to hours. For a geyser to occur there has to be heated rock underground, an abundant source of water, and a "plumbing" system consisting of channels in the ground that conduct water to and up away from the heated rock. Water flowing into the plumbing system is heated many degrees over its boiling point. Eventually the pressure of the heated water increases to the point that water and steam will be rapidly ejected into the air. Eventually, the plumbing system will restock itself with water and repeat the process again.
Liquid nitrogen geysers have been observed on Neptune's moon Triton (these are believed to erupt via a different mechanism than here on Earth). A small liquid nitrogen geyser can be made by placing a meter-long copper tube partially into a pool of liquid nitrogen. The tube at room temperature is inserted into the Dewar flask that contains some liquid nitrogen. Since the boiling point of liquid nitrogen is 77K and the tube is approximately room temperature (298 K), liquid nitrogen entering the tube will quickly vaporize, pushing vapor and liquid nitrogen up the tube into the air for a brief time.

Reference:

Wikipedia: Geyser. http://en.wikipedia.org/wiki/Geyser (accessed June, 2006).

BELOW: A liquid nitrogen geyser. The copper tube shown here is 120 cm long with an inner diameter of 1.4 cm.

Faraday's Candle Chemistry

On the bus this morning I finished reading a copy of Michael Faraday's "The Chemical History of a Candle" based on his famous lecture series over 150 years ago. What an amazing lecturer he was! I had not realized how far back some classic science demos go. My favorite quote:  "We young ones have the perfect right to take toys and make them into philosophy, inasmuch as now-a-days we are turning philosophy into toys." (He was using a suction cup toy to demonstrate air pressure.)  I have not discussed candles much in my lectures, but I have used campfires as examples.

Here is a reference:

Faraday, M.  The Chemical History of a Candle, Sesquicentenary ed., James, F. A. J. L., Ed.; Oxford University Press: Oxford, U.K., 2011.

Geology Demo - Candle Wax Demo

It was noted that when a large candle was placed on a wood stove that the wax in the lower part of candle melted. This melted wax was less dense than the solid, and in some cases rose to the top of the candle and formed flows on the candle surface. This was reminiscent of lava flows in a non-explosive volcanic eruption, so the candle was placed on a small hot plate that could produce more localized heating within the candle. As the pictures show, the melted wax breached the top surface of the candle closest to the center of the hot plate and flowed to the lowest part of the candle surface. When the candle wax cooled and hardened, the remaining liquid wax in the source hole contracted as it became more dense, producing a sort of crater or vent.

BELOW: A candle wax volcano: (LEFT) Liquid wax rising up and almost breaching the top surface of candle. (MIDDLE) The liquid wax "lava" flowing across the candle surface and pooling in a low spot. (RIGHT) When the candle wax cooled and hardened, the remaning liquid wax contracted back into the "vent".

Geology Demo - Snack Layers

To illustrate the Principle of Superposition (oldest rocks are deposited lower than more recent rocks) to a group of Kindergarteners, I poured different types and colors of snack foods into layers into a clear drink pitcher. They seemed to grasp the lowest = oldest connection quite clearly.

Paper Demonstrations

Folded Chiral Paper Structures

Under development. Patterns containing brief instructions on construction and use of these folded paper structures can be downloaded as PDF files from the Internet at: http://bradley.bradley.edu/~campbell/chiralpapersprings.pdf. You are welcome to contact Dean Campbell (http://bradley.bradley.edu/~campbell/campbell@bumail.bradley.edu) to give him feedback on use of this template.

Chemical Cootie Catchers

Patterns containing brief instructions on construction and use of these folded paper structures can be downloaded as PDF files from the Internet at: http://bradley.bradley.edu/~campbell/chemcootiecatchers.html.

 

D. J. Campbell, K. C. Campbell, K. M. Campbell, "Chemical ‘Fortune Tellers’ or ‘Cootie-Catchers’", Chem13 News, March, 2011, 8-9.

Chemical Paper Snowflake Cutouts

 

This paper describes the use of flat paper cutouts with six-fold symmetry for modeling layers of atoms within solid structures. Stacking the cutouts in specific ways illustrates how the layers of the atoms are stacked in the solids. Additionally, these cutouts can be used to demonstrate types of deformation in metals, atomic force microscopy, and carbon nanostructures. These paper lattices can be used on an overhead projector for demonstration to an entire class, or they can be constructed and studied on individual bases by students. K. F. Robinson, P. N. Nguyen, N. Applegren, D. J. Campbell, “Illustrating Close-Packed and Graphite Structures with Paper Snowflake Cutouts” The Chemical Educator, 2007, 12,163-166.

Poisson's Ratio Cutouts Flat, flexible lattices can be used to illustrate Poisson’s ratios of materials. These lattices can be produced from ordinary sheets of paper.
D. J. Campbell, M. K. Querns, "Using Paper Cutouts to Illustrate Poisson's Ratio."  J. Chem. Educ., 2002, 79, 76.

Graphite Cleavage to Graphene Demonstrated with a Deck of Cards

"When a pencil makes a mark on paper, tiny sheets of clay and graphite are rubbed from the pencil “lead” onto the paper fibers.  Recently, scientists have repeatedly split stacked layers of graphite apart (like cutting a deck of cards) to isolate single-atom sheets of graphite.  These single sheets, called graphene, have thicknesses of only a third of a nanometer  – much thinner than the smallest piece of pencil dust." See: http://www.nano.utexas.edu/resources/nano-at-home/.

Chemiluminesent Redox Reaction

This reaction involves a water/acetonitrile solvent, tris(bipyridine)ruthenium(II) ions, ammonium persulfate, and magnesium metal. During the course of the electron transfers in this system, the excited ruthenium complex emits an orange glow near the magnesium metal, producing the appearance of hot coals in the bottom of the reaction vial.

See: White, H. S.; Bard, A. J. J. Am. Chem. Soc., 1982, 104, 6891.

 

ABOVE: Pretty orange chemiluminescence.

Oxidation of Iron Filings in a Sealed Bottle

A couple of years ago I placed coarse iron powder in a sealed bottle to use in magnetism demonstrations. Recently I noticed that the bottle had partially collapsed and hypothesized that it the oxygen in the bottle's air had oxidized the iron to produce iron oxide. I used the volume displacement method (a large graduated cylinder partially filled with water) to estimate the gas volume in the collapsed bottle (405 mL) and in the bottle after allowing air to refill the bottle (490 mL). This represents a percent gas volume change of 17%, which is in the ballpark of the typical 21% oxygen concentration for air.

See: Campbell, D. J.; Bannon, S. J.; Gunter, M. M. J. Chem. Educ., 2011, 88, 784-785.

 

ABOVE: (LEFT) Partially collapsed bottle containing iron powder. (RIGHT) Reinflated bottle containing iron powder.

Coin Batteries

These batteries are simply voltaic piles made by stacking alternating types of coins with filter paper soaked in saturated salt water solution. The metal compositions of pennies are sufficiently different from nickels so that these coins may be used to make weak batteries. More coins can produce more voltage, but there is a tremendous variability in the actual voltage measured. This is likely due to effects such as internal resistance and degree of corrosion on the coins.

See: Scharlin, P.; Battino, R.; Boschman, E. J. Chem. Educ. 1991, 68, 665.

ABOVE: (FIRST) A simple coin battery - a nickel on salt-water soaked filter paper on a penny. (SECOND) Measuring the potential of a single pair of coins (in millivolts). (THIRD) Measuring the potential of multiple pairs of coins (in millivolts).

Vitamin C Redox Reaction Cleans Up Iodine Stains on Hand

I learned this demo from a visitor to campus a couple years ago. This demo takes only a couple minutes. To put this together, you need to go to the local drugstore/grocery store and pick up the following:

-iodine solution (tincture of iodine, used as a disinfectant)

-spray starch

-vitamin C tablets

Step 1 - Smear some of the iodine solution on the palm of your hand. DO NOT let the iodine solution dry out (otherwise it will be hard to remove).

Step 2 - While the iodine solution is still wet, spray some starch onto the palm of your hand. The iodine spot turns blue-black as the starch molecules wrap around the iodine molecules. Again, DO NOT let this mess on your hand dry out.

Step 3 - While the iodine/starch solution is still wet, take a vitamin C tablet and rub it across the stain (I make a smiley face first). The dark stain disappears though sometimes there might still be some yellow tint left. The vitamin C tablet acts as an antioxidant, reducing the iodine to iodide ions and breaking apart the starch/iodine complex. The tablet itself stays fairly white, this it not simply rubbing the stain off, it is a chemical reaction.

CAUTIONS:

Wash your hands with soap and water as soon as you get the chance after the demo (the starch on your hand will still be sticky/slimy).

Iodine stains all sorts of things, so do not spill it.

DO NOT eat the vitamin C tablet that you used in the demo, though you should be able to use the same tablet multiple times.

You should try this demo by yourself first in case I missed any subtle details.

VARIATION: A counterfeit money marking pen, which apparently contains iodine, can be used instead of tincture of iodine. The iodine in the pen does not react with the cloth fibers in real money, but it does react with the cellulose fibers in counterfeit money. The pen can be used to draw light tinted patterns on skin, but the markings dry out fairly quickly so the starch must be applied quickly to turn them dark. These starch/iodine marks can also be erased with a vitamin C tablet.

ABOVE: (LEFT) Step 1 (MIDDLE) Step 3 and (RIGHT) Variation: Erasing counterfeit money pen marks.

Liquid Nitrogen Soap Suds Explosion

I saw this demonstration on the "David Letterman Show" and just had to try it. It simply involves quickly pouring liquid nitrogen (WARNING: Extremely COLD!) into hot water (WARNING: HOT!) containing dishsoap. The liquid nitrogen flashes to nitrogen gas, causing a large explosion of rather cool soap suds. This demonstration is best done outside since so many suds are produced. An awesome demonstration of phase changes!

BELOW LEFT: The soap suds explosion.

BELOW RIGHT: Aftermath of the soap suds exposion. I got suds all over me from this one (note the suds on the step rails and on the ground).

Kylee Korte, Phuong Nguyen, and Joel Kouakou assisted in preparing this description.

CAUTION: Liquid nitrogen is very cold and presents a serious frostbite hazard, especially if it gets trapped against your skin (e.g.in your clothing). Additionally, gaseous nitrogen occupies more volume than the same quantity of liquid nitrogen. Gaseous nitrogen produced quickly enough in sufficient quantities can displace oxygen from the air. Containers filled with liquid nitrogen could fail without warning due to thermal shock or gas pressure. Protect yourself accordingly.   For a scary story about liquid nitrogen hazards, see: http://www.wpi.edu/news/19989/nitro.html.

Leidenfrost Effect with Liquid Nitrogen

Named after Johann Gottlob Leidenfrost, a German doctor, the Leidenfrost Effect is an occurrence where a liquid comes in contact with a material that is much hotter than its boiling point and creates a vapor layer to prevent it from further direct contact with the material. The liquid then boils much more slowly as it is protected by the insulating vapor layer. Liquid nitrogen on a smooth surface at room temperature can illustrate this phenomenon. The liquid nitrogen is obviously the liquid and the surface is the material that is much hotter than it. Droplets of the liquid nitrogen will move easily across the surface, supported on cushions of nitrogen vapor.

Reference:

Wikipedia: Leidenfrost effect. http://en.wikipedia.org/wiki/Leidenfrost_effect (accessed May, 2012).

BELOW: Droplets of liquid nitrogen exhibiting the Leidenfrost effect.

 

Kylee Korte, Phuong Nguyen, and Joel Kouakou assisted in preparing these descriptions.

CAUTION: Liquid nitrogen is very cold and presents a serious frostbite hazard, especially if it gets trapped against your skin (e.g.in your clothing). Additionally, gaseous nitrogen occupies more volume than the same quantity of liquid nitrogen. Gaseous nitrogen produced quickly enough in sufficient quantities can displace oxygen from the air. Containers filled with liquid nitrogen could fail without warning due to thermal shock or gas pressure. Protect yourself accordingly.   For a scary story about liquid nitrogen hazards, see: http://www.wpi.edu/news/19989/nitro.html.

Homemade Shrinky Dinks®

Transparent polystyrene packaging such as those used to hold baked goods can be used to make plastic trinkets. (Not all clear packaging works. Polystyrene containers should have a number 6 inside the recycling triangle on the plastic.) When the plastic is heated, stretched-out polymer chains have enough energy to relax their orientations. As a result, thin flexible sheets of the clear polystyrene will shrink laterally, thicken, and become less flexible. Writing that was placed on the surface of the polystyrene with permanent markers will also shrink. This polymer behavior is the basis for Shrinky Dinks®, a craft/toy that was popular in the 1970s and 1980s, and can still be purchased today.

®Shrinky Dinks is the Registered Trademark of K & B Innovations, Inc.

 

ABOVE: The polystyrene "windows" on envelopes can be used to make Shrinky Dinks®. Before (LEFT) and after (RIGHT).

BELOW: Patterned polystyrene sheets before (LEFT) and after (RIGHT) being placed in an oven. Use a relatively low temperature (about 65 C) or they will melt rather than shrink! NOTE: Many but not all sheets of polystyrene will shrink and not all sheets will shrink equally in all lateral directions.

BELOW: Making clear polystyrene icicles. There is a significant burn risk here. A polystyrene sheet placed on aluminum foil in a toaster oven at 300 F or simply to "toast" mode will shrink fairly quickly (it is fun to watch - but don't leave them in the oven too long or they might melt). A narrow triangle of polystyrene container material, with a hole punched in the top, is shown at LEFT. The wrinkles usually flatten out upon heating. While the shrunken sheets are still hot, remove them from the oven, twist them quickly into a spiral shape, and hold until they have cooled, as shown at RIGHT. If the shape of the twist is unsatisfactory, placing the icicle back into the oven will untwist it. Again, there is a significant burn risk here. My wife loaned me her thimble to provide a measure of protection.

MORE BELOW: One can make interesting faces on polystyrene sheets, shrink them, and attach them to pom-poms. (Hot melt glue works much better than school glue for this.) Placing a magnet on the back enables the decoration to stick to a refrigerator door. The picture below includes a couple versions of moles (a popular mascot for chemists) and a tomato cartoon character that is popular in the Campbell household.