Unlocking the Secrets of Invisible Ink

Have You Ever Wondered …

How does invisible ink work?

What common household substances can be used to make invisible ink?

What things can you do to reveal a message written in invisible ink?

Steganography is the practice of concealing a file, message, image, or video within another. The use of invisible inks is one of the earliest known examples of steganography. Invisible ink today is mostly considered child’s play, but in the not too distant past, its use and the recipes were considered classified government information.

Using the suggested inks and reagents provided here, write a secret message to a friend. Then get creative and see how many kinds of invisible ink you can find.Unlocking the Secrets of Invisible Ink @EvaVarga.net

Types of Invisible Inks

There are two categories into which invisible inks fall ~ organic fluids and sympathetic inks. You can find many heat-activated invisible inks right inside your kitchen. Another type of invisible ink is chemically activated. Read on to learn more about each.

Organic or Heat-Activated Invisible Inks

Organic fluids consist of the natural methods your likely already familiar: lemon juice, vinegar, milk, or onion juice, to name a few. These organic invisible inks can be revealed through heat, such as with fire, irons, or light bulbs.

The organic fluids alter the fibers of the paper so that the secret writing has a lower burn temperature and turns brown faster than the surrounding paper when exposed to heat. To activate or develop the ink, simply iron the paper, set it on a radiator, place it in an oven (set lower than 450° F), or hold it up to a hot light bulb.

  • any acidic fruit juice (e.g., lemon, apple, or orange juice)
  • onion juice
  • sodium bicarbonate NaHCOsolution (baking soda)
  • vinegar
  • white wine
  • diluted cola
  • milk
  • soapy water
  • sucrose solution (table sugar)
  • bodily fluids

solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute (baking soda or sugar) is a substance dissolved in another substance, known as a solvent (water).

Inquiry Science :: What other organic inks can you find? Which kind shows up best? Which kind lasts longest?

Unlocking the Secrets of Invisible Ink @EvaVarga.net

Sympathetic Inks

Sympathetic inks contain one or more chemicals and require the application of a specific “reagent” to be activated, such as another chemical or a mixture of chemicals. Most of these inks work using pH indicators, requiring the recipient to paint or spray a suspected message with a base (like sodium carbonate Na₂CO₃ or washing soda solution) or an acid (like lemon juice). Some of these inks will reveal their message when heated.

  • lemon juice, activated by iodine solution
  • starch (e.g., corn starch or potato starch), activated by iodine solution
  • vinegar or dilute acetic acid CH3COOH, activated by red cabbage water
  • ammonia NH3, activated by red cabbage water
  • sodium bicarbonate NaHCO3 (baking soda), activated by grape juice
  • sodium chloride NaCl (table salt), activated by silver nitrate
  • phenolphthalein (pH indicator), activated by ammonia fumes or sodium carbonate Na₂CO₃ (or another base)
  • lead nitrate, activated by sodium iodide
  • iron sulfate, activated by sodium carbonate, sodium sulfide, or potassium ferricyanide

CAUTION: Some of the chemicals suggested here can be hazardous if misused. Always use caution when working with chemicals. Read the information on the chemical label before you start, and always wear protective safety equipment such as goggles, gloves, and aprons. Adult supervision required.

Ultraviolet Light Activated Invisible Inks

Most of the inks that become visible when you shine an ultraviolet or black light on them will also become visible if you heat the paper. Here are are few ‘glow-in-the-dark’ ideas to try:

  • dilute laundry detergent (the bluing agent glows)
  • tonic water (quinine glows)
  • vitamin B-12 dissolved in vinegar

The History of Invisible Ink

The history of invisible ink is incredibly fascinating and swings wildly between high-tech methods and the humblest of approaches. Invisible ink was a key method for spy communications throughout history. Prisoners, Lovers, and Spies is an historical account of invisible ink and the secret communications revealed through thrilling stories about scoundrels, heroes, and their ingenious methods for concealing messages.

The Catholic Mary, Queen of Scots, kept under luxurious house arrest for eighteen years by her Protestant cousin Elizabeth I, advised correspondents to write to her employing two commonly used substances: alum (hydrated potassium aluminum sulfate) or nutgall (the tannic acid secreted in swellings generated by parasitic wasps colonizing oak trees). Letters written in alum required the recipient to soak the paper in water, while nutgall needed a solution of ferrous sulphate as a reagent.

During World War II, chemist Linus Pauling worked on an unusual wartime project, formulating new kinds of invisible ink that would resist all known reagents. Pauling and his colleagues experimented with invisible inks made from pneumococcus bacteria (an inert strain so as not to spread pneumonia). The ink-ified microbe would react to an antibody, and then become visible once dipped in a dye solution. However, the ink never passed the experimental stage.

Visit The Art of Manliness for a more detailed look at how invisible inks have been used in espionage and naval intelligence.

Wildlife Biology for Middle School: Develop Skills with Animal Cams

animalbehaviorWildlife Biologists are scientists that observe and study the behaviors of animals. They frequently observe the features of certain wildlife and determine the role these animals have in their specific ecosystems. Many Wildlife Biologists specialize into a particular area of study defined by ecosystem or species. Some of these fields include: Entomology (insects), Ichthyology (fish), Ornithology (birds), or Marine Biology.

Youth interested in learning more about animals and the study of wildlife can learn a great deal from the comfort of their home via a webcam. Though limited in scope, animal cams can provide a glimpse into the lives of animals and are one tool to help develop our understanding of animal behavior.

I have compiled a list of some of my favorite animal cams from around the world. Take time to browse them all or utilize the printables I’ve provided below to develop a more in-depth wildlife biology study on your favorite animal.

ethologyOur Favorite Animal Cams

Birds

Bald Eagles

Location: Decorah, Iowa
Best time to watch: Eggs may begin hatching between March 25 and March 29 based on a 35 to 39 day incubation period.

The Decorah bald eagles nest atop a large white oak tree in a secluded valley. Their eggs hatch roughly 35 days after they are first laid, which means that three eggs within the nest right now are due any time now.

Location: Turtle Bay Eagle Cam (Redding, California)

We became captivated by this breeding pair when we first moved to Redding in 2011. The female Bald eagle has successfully fledged 14 eaglets and in 2015 had 3 youngsters in the nest!  This is not the first time she has done this, as she did the same in 2009 and 2010.  Only 5% of Bald eagles successfully lay and fledge three eaglets. Though this animal cam is currently offline (the eagle pair have moved), their story is fascinating.

Hummingbirds

Location: La Verne, California
Best time to watch: March (chicks are hatching any minute)

Bella the Hummingbird has been nesting for more than 10 years. Her nest is about the size of a golf ball, and her eggs are only about the size of a mint. Every spring she lays eggs and a couple weeks later the world watches new life being born. This year, she last laid her eggs on the 6th and 8th of March. When I checked in with her as I wrote this post, they’d recently hatched.

Great Horned Owls

Location: Montana
When will you see babies? Due in roughly 2-3 weeks.

The Montana owlets are due two or three weeks from now. Since owls are nocturnal, this is a live feed worth checking out later at night when the other animal cams have little or no activity.

Spotted Owls

Location: High Desert Museum (Bend, Oregon)

When we lived in Bend, the spotted owl pair at the High Desert Museum were receiving a lot of media attention. It had previously been believed that Spotted Owls required old growth forest to survive yet here were a rehabilitated pair who had successfully reared several consecutive clutches of chicks. Sadly, I believe the owl cam is presently offline.

Penguins

Location: Aquarium of the Pacific (Long Beach, California)
Best time to watch: All the time.

The above the water cam shows the edge of the rocky beach, where penguins hop in and out of the water. You can watch as they swim and float on the surface. They also have a below the water cam to view the penguins as they dive and dart below the surface.

Mammals

Bears

Location: Katmai National Park, Alaska
Best time to watch: In July when their babies are born.

A mama bear and her three bear cubs is what you’ll get if you tune into the Brooks Falls animal cam, which features big shaggy brown bears catching fish, wading around, and just generally having a good time in Alaska’s Katmai National Park. Since bear cubs are only due in July, this cam currently hosts a continual stream of highlights gathered from several live cams.

Manatees

Location: Blue Spring State Park (Maitland, Florida)
Best time to watch: Winter and early Spring
We first discovered the Save the Manatees Club when we were planning a family holiday to the Florida Keys. Though the manatee season has ended, favorite clips are still accessible. The live cams will resume again next season.

Sea Otters

Location: Monterey Bay Aquarium (Monterey, California)

You can watch sea otters here from 7 a.m. to 7 p.m. Pacific Time. Daily feeding times are 10:30 a.m., 1:30 p.m., 3:30 p.m. And who knows? Maybe you’ll spot an otter pup somewhere in there.

Sloths

Location: Atlanta, Georgia

This sloth cam, part of Zoo Atlanta, lets you become virtual best friends with two-toed sloth Cocoa, his lady friends Okra and Bonnie, and baby sloth Raisin. Though it’s currently offline, you can still log in at 1:30 pm ET every other Wednesday for sloth chats.

Reindeer

Location: “North Pole”
Best time to watch: Holiday season
Reindeer who aren’t employed by St. Nick live in the colder climates of North America and Europe where they feast on a diet of moss, leaves, and grass. They are sometimes referred to as Caribou in Canada.

Fish

Sea Dragons

Location: Aquarium of the Pacific (Los Beach, California)

Found only in Australian coastal waters, Sea Dragons are bony fish related to seahorses, pipefish, and seamoths.

Invertebrates

Jellyfish

Location: Aquarium of the Pacific (Los Beach, California)

Few things are more calming than watching these serene, colorful jellyfish float their lives away.

Ecosystems

Kelp Forest

Location: Monterey Bay Aquarium (Monterey, California)

Watch this underwater kelp forest cam to see an astonishing array of diverse fish and invertebrates. If you’re lucky, you’ll see a wolf-eel chow down on a squid or some fish.

Coral Reef

Location: National Aquarium (Baltimore, MD)

African Savanna

Mpala Live – Meet the animals that roam Mpala in Kenya’s Laikipia area. Their website also provides field guides, lesson plans, and activities that you can download free to get more out of your viewing.

~ ~ ~

For a comprehensive collection of animal webcams, visit Live Animals TV, the world’s largest collection of animal webcams.

wildlifebiologyWildlife Biology Lesson Plans & Printables

I have put together a simplified ethogram or inventory of behaviors and actions exhibited by an animal. The free printable will be available for my newsletter subscribers later this week. Take a moment to subscribe today. It will be available only for a limited time.

Most aquariums, zoos, and wildlife centers around the country have developed activity guides and animal observation lessons. You’ll find curriculum and materials for many of the animal cams shared above at the original host site. Many of these can be modified for use with animal cams as well as during your site visit. Browse their education links to see what you can find.

e·thol·o·gy
noun: ethology
  1. the science of animal behavior.
    • the study of human behavior and social organization from a biological perspective.

The Lincoln Park Zoo in Chicago, Illinois provides a wonderful Zoo Observation Data Sheet whereby students use an ethogram-based data sheet to record animal behavior. Thereafter, students use the data they have collected to develop their own animal behavior research project. Their materials can be adapted to wildlife viewing locations around the world.

You may also wish to download this very informative Animal Behavior slide show presentation to become familiar with the range of animal behavior and understand the methods that ethologists use to study animal behavior.

 

Make Your Own BioPlastics

bio plasticsPlastics play an important role in our lives.  Plastics are used to manufacture many everyday items and have significantly reduced the use of glass.  Some plastics are very durable and make things like furniture and appliances.  Other plastics make items such as diapers, trash bags, cups, utensils and medical devices.  The largest amount of plastic is used to make containers and packaging for items such as soft drink bottles, lids, shampoo bottles, etc. Common plastic is made from petroleum, a fossil fuel which is nonrenewable.

Nonrenewable resources are made naturally by the earth, but do not renew themselves fast enough to be able to count on having the resource for an indefinite period time.  Some resources are considered non-renewable because our access to the resource is limited.  For example, glass and metal are non-renewable resources.  The elements and minerals used to make glass and metal are found in the structure of the earth’s crust, however we are limited to what we can access through mining.

Renewable resources are either naturally reproduced at a sustainable rate or they can be produced in agriculture at a rate equivalent to the demand or need.  For example, corn can be used for ethanol fuel and to produce corn oil.  Corn is a renewable resource.

DIYBioPlasticsBioplastics are a type of plastic made from renewable, biological materials like starches, cellulose, oils or proteins. They generally contain little to no petroleum and therefore are usually biodegradable. When bioplastics are exposed to the environment (sunlight, heat, water, microorganisms) they breakdown into non-toxic compounds like carbon dioxide and water. Additionally, unlike petroleum-based plastics, bioplastics are made from renewable resources. These resources are typically agricultural byproducts, like cornstarch and potato starch, tapioca starch and casein (milk protein).

Biodegradable: refers to material capable of breaking down into harmless products through the action of living organisms or natural processes

Byproducts: in agriculture refers to secondary products created from a crop. For example, corn starch is a byproduct of corn

Make Your Own BioPlastics

Materials

  • Plant based oils (Corn Oil, Sesame Oil, Vegetable Oil)
  • Cornstarch
  • Water
  • Food coloring
  • Measuring spoons
  • Eyedropper (optional)
  • 1 Ziploc bag per student
  • Access to a microwave oven

BioPlasticsProcedure

  1. Place the following ingredients in a plastic bag: 1 tablespoon of cornstarch, 2 drops of oil, 1 tablespoon of water, and 2 drops of food coloring.
  2. Seal the bag and gently mix the cornstarch mixture by rubbing the outside of the bag with your fingers until combined.
  3. Open the bag slightly, making sure it can vent. Place the bag in a microwave oven on high for 20-25 seconds.
  4. Carefully remove the bag from the microwave and let it cool for a few minutes. While it is still warm, students can try to form their plastic into a ball. Observe what it does.
  5. Ask them to describe their plastic; did it turn out differently than others? Does the type of oil you used affect the bioplastic? Have the students name three things they could make with bioplastic.

Take it Further

I’m committed to sharing activities and resources for teaching science in your homeschool. I believe it is helpful to see that science isn’t scary and it doesn’t require special curriculum. Here are a few resources that you can use to further your study of plastics and renewable vs. nonrenewable resources.

Watch the 3-minute How Stuff Works video clip about Corn Plastic.

In this hands-on, inquiry based Plastics Lab Activity, students investigate whether all plastics the same? How are they different?

Polymers Are Cool ~ Experiment with different polymers, large molecules composed of many repeated subunits, with these 3 great recipes.

As plastics are not biodegradable, learn how you can make a difference in encouraging others to reduce our use of plastics. The volunteers at Washed Ashore inspired us to create a Bottle Cap Mural to help spread the word of the harm done to our oceans by plastics.

 

Whale Watching on the Oregon Coast

A few months ago, I shared a number of Great Spots to Watch Oregon’s Winter Storms. But winter storms are not the only thing that draws the crowds to our shoreline. Gray whales, which migrate farther than any mammal on Earth, can also be observed and volunteers all along the coast are eager to share their knowledge with you. Whale watching takes place almost year-round on the Oregon Coast.

Whale Migration

Each winter in the warm waters of Mexico, gray whales give birth, nurse their calves, rest and play before their long journey north in spring. They swim 5,000 miles along the Pacific coast from Mexico to the waters of the Arctic. The trip ends in the nutrient-rich feeding grounds of the Bering Sea in Alaska. In fall, they travel back to Mexico again to complete a round trip annual journey of 10,000 miles.

DepoeBayWe enjoyed a little weekend getaway this past weekend, driving north along Highway 101 to Newport. We stopped at numerous scenic points along the way to observe the waves crashing on rocky shoreline. In Depoe Bay, we visited with the Oregon Parks and Recreation volunteers who helped us to spot the gray whales migrating offshore.

The first phase (non-calves) of the northbound gray whale migration appears to have peaked and the second phase (moms with babies) is just beginning – just in time for Spring Whale Watch Week, March 19 – 26.

Whale Anatomy

Listed in the National Register of Historic Places, the Whale Watching Center in Depoe Bay was constructed during the postwar period designed to serve the rapidly increasing ranks of the motoring public, while taking advantage of a unique scenic vista—the world’s smallest navigable harbor at Depoe Bay.

While here, we also took time to enjoy the touch tables and pictorial history inside the center. What fascinated me most was the whale ear bone pictured here.

whaleearbone

In land mammals, the fleshy pinna or the outside part of the ear helps collect sound and funnel it into the ear. That works because the acoustical properties of the air and flesh are different, so sound  gets channeled into the ear canal where it vibrates the eardrum and the ossicles (or ear bones).

In water, the acoustical properties of flesh and water are pretty similar, therefore the fleshy outside part of the ear serves no function. Though hearing in baleen whales is not well understood, in toothed whales, instead of sound coming in through the ear canal, sound comes in through fatty tissues in the jaws which are attached to an acoustic funnel. Scientists believe that the ossicles vibrate this fluid-filled inner ear.

whalebaleen

Baleen whales like the Grey Whale do not have teeth, instead they have 130 to 180 baleen plates that hang down each side of their upper jaws, like a fringed curtain. The plates are made out of fingernail-like material called keratin, the same substance found in human fingernails and hair. It makes the baleen strong, but still flexible.

Baleen is a filter-feeder system inside the mouths of baleen whales. The baleen system works when a whale opens its mouth underwater and the whale takes in water. The whale then pushes the water out, and animals such as krill are filtered by the baleen and remain as food source for the whale.

Inside the center, there was also a display that discussed how man has hunted the whale in the past for oil and baleen. It provided a fascinating reflection of how man has impacted our natural resources and how times have changed.

depoewildlifeOther Wildlife

Whales are not the only wildlife one can observe here at the Whale Watching Center. In addition to the whales we glimpsed with spotting scopes, we also observed the following at wayside viewing center:

  • Black Oystercatcher Haematopus bachmani
  • Black Turnstone Arenaria melanocephala
  • Pelagic Cormorant Phalacrocorax pelagicus
  • Several species of gulls
  • Ground Squirrel – species yet unidentified, but resembles Belding Ground Squirrel (Spermophilus beldingi)

Whale Watching Sites

Beginning north and traveling south along highway 101, the following locations are excellent view points from which to watch for whales.

  • Lewis & Clark Interpretive Center, Cape Disappointment State Park
  • Neahkahnie Mountain, south of Cannon Beach
  • Cape Meares State Park
  • Boiler Bay State Scenic Viewpoint
  • The Whale Watching Center, Depoe Bay
  • Cape Foulweather
  • Cape Perpetua Stone Shelter
  • Sea Lion Caves Viewpoint
  • Umpqua River Whale Watching Station
  • Shore Acres State Park
  • Cape Arago State Park
  • Face Rock State Park
  • Battle Rock Wayfinding Point
  • Cape Sebastian
  • Klamath Overlook

For more detailed information on Whale Watching, download the brochure from the Oregon Parks and Recreation Department.

Discovering the Joy of Maple Sugaring at Home

Most people don’t realize that the Sugar Maple is not the only tree that yields syrup. We had thoroughly enjoyed our first experience maple sugaring when the kids were toddlers. Now that we have returned to Oregon, we are delighted to revisit our sugaring experience with Tap My Trees.bigleafmaple

We received a Tap My Trees starter kit in exchange for an honest review. I also received monetary compensation for my time spent in reviewing the product.  All opinions expressed are true and completely our own. Please see my disclosure policy for more information.

There are 13 species of maple trees that grow in the United States. The Sugar Maple (Acer saccharin), one of America’s best-loved trees, is the most well known due to its historical and economical importance.In Oregon, Sugar Maple is an ornamental and found only on college campuses and occasionally in someone’s yard. Oregon’s most prevalent native maples are Bigleaf Maple (Acer macrophyllum) and Vine Maple (Acer circinatum). Learn more about Our Native Maples in my earlier post. 

bigleafOur Maple Sugaring Experience

I shared a more in-depth look at Science of Sugaring a few months ago. From everything we have read and from our past experiences, we knew that sap would immediately start to flow after tapping the tree if the weather conditions were just right. Cold nights and warm days were what we needed.

We waited. We watched the forecast. Then my dad telephoned, “This week looks to be a good time to go sugaring?!” Yippee! We gathered our gear and piled into his truck.

Oregon Geography

The Oregon Coast is bordered on the west by the Pacific Ocean and the Pacific Coast Mountain Range on the east. It is 30 to 60 miles (48 to 97 km) wide and averages around 1,500 feet (460 m) in elevation above sea level. Temperate rain forests with high peaks and steep ridges dominate this region.elliotstateforest

In the southernmost section of the Coast Range where we live, you can find the Elliott State Forest. The forest is home to over 50 mammal species, over 100 species of birds, and nearly 30 reptile or amphibian species that spend significant portions of their life cycle in the mountains. It is here that the Big Leaf and Vine Maples grow.

Tapping the Trees

It took about an hour to drive up to the forest and locate the Big Leaf Maples. We found a several in the mid elevations on relatively dry slopes. As the terrain is so steep, most were out of our reach but we did manage to find a couple near the road. Sadly, when we tapped them, the sap was not running. Dad said this was an ominous sign but we hung our bucket anyway and gave it a go.

rainforestWe then drove to a lower elevation in a narrow, moist valley where we located a grove of Vine Maple. You can see in the photo above the abundance of ferns and bryophytes in the understory. When we tapped the Vine Maple, the sap started flowing immediately.

Maple sap is a clear fluid and resembles water. The collection amount may vary. Some days you will collect only a small amount and other days your buckets may overflow if not emptied.

We thereby hung several bottles amongst the vine maple shrubs that covered the hillside. For these smaller trees, we recycled a plastic soda bottle by poking a hole in the side and sliding the bottle onto the spile.

vinemaple

Collecting the Sap

We returned a few days later to retrieve our materials and any sap we collected. Much to our chagrin, the bucket on the Big Leaf was dry. It was just the wrong time. We’ve wanted to try again but the weather hasn’t been very cooperative this year. We’ve had an unseasonably warm winter and lots of rain.

The vine maples, however, were more cooperative. We collected about a quart of sap which when processed yielded only about 2 tablespoons of syrup. Enough for one pancake serving anyway. We all agreed it was very similar to the pure syrup we purchase, but with a little more tangy taste.

It is clearly much more work and effort to tap trees in Oregon, thus making the endeavor economically disadvantageous. This is due in part to the difficulty in reaching the trees but also that a larger quantity of big leaf or vine maple sap is needed to produce equivalent volumes of syrup than the sugar maple.

However, I highly recommend the sugaring experience to families, especially if you have access to maple trees where you live. It is great opportunity to get outdoors and bond together over shared memories – not to mention all that one can learn through the process.

While 2016 wasn’t a good year for tapping the Big Leaf Maple in Oregon, we’ll be sure to try again next year. Sugaring has become a lifelong hobby everyone in our family enjoys.

Maple Sugaring with Tap My Trees

Tap My Trees is the #1 provider of sugaring supplies for the hobbyist. Devoted to educating families about the practice of maple sugaring Tap My Trees has made donations of supplies to nature centers hosting maple sugar events and they’ve made quite a few products available for teaching Maple Sugaring at Home.

They offer 4 starter kits with the highest quality supplies to tap maple trees at home. You can also customize your kits by ordering sugaring accessories individually. The instructive guidebook outlines the steps to making the maple sugar and contains all the information you need for a successful sugaring from identifying the appropriate tree to how weather affects the sap run, when to collect, and how to boil down the sap.

The lesson plans also include a timeline beginning in the winter and go month by month listing the topics for each month leading to the sap collection and syrup making. Sugaring is a fabulous unit study covering botany, ecology, meteorology, physics, and even history!

Connect with Tap My Trees

Tap My Trees is committed to sugaring education and they provide recipes and other information on social media. Their products are also available on Amazon, if you prefer. Be inspired!

Facebook § Twitter § Instagram § Pinterest

Polymers Are Cool: 3 Recipes for Middle School

Chemistry is great for making many useful products. It’s also good for making stuff that’s just fun to play with. One of my favorite chemistry units is on polymers.

A polymer is a large molecule, or macromolecule, composed of many repeated subunits. In other words, they are made up of many, many molecules all strung together to form really long chains.

Polymers Are Cool: 3 Polymer Recipes for Middle School @EvaVarga.netIn Greek, Poly- means “many” and -mer means “part” or “segment”.  Mono means “one”. So, monomers are the individual molecules that can join together to make a long polymer chain.

A single polymer molecule is made out of hundreds of thousands (or even millions!) of monomers. Not all molecules can link up in this way to form polymers, however.

The atoms that make up a polymer chain essentially line up and repeat all along the length of the polymer chain. For example, look at polypropylene:


Polypropylene is made up of just two carbon atoms repeated over and over again. One carbon atom has two hydrogen atoms attached to it, and the other carbon atom has one hydrogen atom and one pendant methyl group (CH3).

In this example, the pendant group hangs from the carbon atom in the chain backbone. As you can see from the example, pendant groups usually repeat along the length of the chain as well.

But enough of the mumbo jumbo. Let’s get to the fun stuff. What is better than reading about chemistry? Doing the labs, of course!  Here are three tried and true recipes for polymers you can use in the classroom.

Polymer Recipes ~ Get Messy!

Basic Polymer Putty

This is a fun and easy polymer to make (and the one featured in the photographs).

Materials

  • Elmer’s white glue
  • Borax (find in the laundry detergent aisle of the store)
  • Water
  • Two bowls
  • Food coloring (just for fun)

Procedure

  1. In one bowl mix 1/2 cup (4 oz) glue and 1/2 cup water. Add food coloring if you want colored slime.
  2. In the other bowl, slowly mix borax into 1 cup of water until the borax will no longer dissolve (this is a saturated solution).
  3. Add the glue mixture to the borax solution, stirring slowly.
  4. The slime will begin to form immediately; stir as much as you can, then dig in and knead it with your hands until it gets less sticky.  Don’t worry about any leftover water in the bowl; just pour it out.

The glue has an ingredient called polyvinyl acetate, which is a liquid polymer. The borax links the polyvinyl acetate molecules to each other, creating one large, flexible polymer. It will get stiffer and more like putty the more you play with it.

Store it in a plastic bag in the fridge, to keep it from growing mold.

polymer recipesA Firmer Polymer

This recipe makes a firmer, dryer slime that will even bounce if it is kneaded enough.

  1. Mix 4 tsp. (20 ml) water with 5 tsp. (25 ml) Elmer’s or other white glue in a small bowl.
  2. Add 1 tsp. (5 ml) talcum powder and stir until thoroughly mixed.
  3. Add 1 or 2 tsp. (5 or 10 ml) saturated borax and water solution. Stir four a few minutes.
  4. Remove the glob from the bowl and stirrer. Knead it for a while and it will become drier.

You will probably need to wipe off some of the excess moisture from your hands with a paper towel from time to time. Don’t be tempted to wipe the glob with a paper towel as it will only stick. You can add a little talcum to the surface if you are having trouble getting it dry enough. Store in a zip lock in the fridge.

plastics lab activityTake a closer look at plastics & polymers

Super Slime

This slime is similar to the one above, but creates a less rubbery and more transparent slime. This is the real gooey deal! (This slime is non-toxic, but still keep these chemicals away from unsupervised children and wash your hands after playing with the slime.)

Materials

  • Polyvinyl Alcohol (PVA)
  • Borax
  • Water
  • Graduated cylinder or measuring cups and spoons
  • Food coloring (just for fun)

Procedure

  1. Make a 4% solution of polyvinyl alcohol: Stir 1.5 teaspoons (approx. 4g) of PVA into 1/2 C (approx 100 ml) of water in a large microwave-safe bowl. Cover the bowl and microwave for 1 minute, then stir. Microwave another 30 seconds and stir. Continue until all the PVA is dissolved. A slight film may have formed on top; you can remove that with a spoon. You can add food coloring if you want colored slime. Allow the solution to cool.
  2. Make a 4% borax solution by stirring a little less than 2 teaspoons (approx. 4g) of Borax into 1/2 cup of water.
  3. Pour the cooled PVA solution into a ziplock bag and add 2 teaspoons (10ml) of the borax solution.
  4. Zip the bag and knead it until the chemicals are mixed into slime. Then scoop it out and play with it.

While water is a liquid made up of individual H2O molecules, polyvinyl alcohol is formed of long chains of connected molecules, making it a liquid polymer. The borax acts as a “cross-linker,” linking the individual PVA chains to each other. The borax molecules form hydrogen bonds with molecules present in the PVA chains. The partial positive charge of hydrogen atoms attracts the partial negative charge of oxygen atoms. Since hydrogen bonds are weak, they can break and reform as you play with the slime or let it ooze on a flat surface.

Your slime will last for a while if you seal it in a plastic bag and keep it in the fridge.

Misconceptions in Chemistry @EvaVarga.net

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Helpful Hints for Success with Polymers

Gel type glues

Over the past few years several brands of gel type glues have been introduced. Most of these make excellent slimes which are very elastic and have a nice color and consistency. I have personally experimented with Elmer’s School Glue Gel, but there are several similar products available from other manufacturers. Try substituting a gel glue in the Basic Polymer recipe, above.

Slime overly sticky or runny?

If your white glue or gel glue based slime is too sticky or runny, first try kneading it for a while. Working it in your hands will help to mix things up better, as well as remove some of the moisture. If it is still not quite right, mix 1 part borax with 10 parts water. Dunk the slime into this solution, remove and knead.

Precautions

  • Polymers can wreak havoc with plumbing, so don’t throw them down the drain.
  • Always wear a mask when mixing PVA.
  • Use distilled water for all solutions for best results.
  • Keep polymers away from anything they could damage. They can dry into fabric and the dyes can stain surfaces, including wood.
  • Supervise small children when playing with polymers so they do not ingest any.
  • Some people are allergic to Borax powder. Wearing rubber gloves when mixing should help.
  • Polymers using Borax solutions work best if you pour the Borax solution into the other solution, rather than the other way around. Coloring should be added before the Borax.
  • Use metric measurements whenever possible. This will make it simpler to experiment with different concentrations and ratios.

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