Science of Slime
That’s right! Get ready for six full weeks of the slimiest history, gooiest facts, and the most amazing science behind the slime that everyone is talking about. (August 23rd – September 27th)
Part 1 - The Elevator Pitch Version
This is a simplified, elevator-pitch version of PVA slime science if you’re in a hurry.
Most liquids, such as water (H2O), are made up of separate, unconnected molecules moving around and tumbling over and bouncing into and off of one another. These single, unconnected molecules are called monomers (mono = one). Monomer liquids – like water – flow easily and are seldom gooey or sticky.
In other substances, identical monomers are chemically bonded into very long, separate chains of many molecules called polymers (poly = many). These long chains don’t often flow like water; they’re gooier and may even ooze a little. Imagine a bowl of tiny steel chains. The chains can roll over and around one another but they are still long and separate. One chain is not hooked to another chain. If you grab one chain and pull it out, that’s what you get: one chain. Liquid polymers tend to flow more slowly than liquid monomers. Polyvinyl alcohol (PVA) and is a liquid polymer. It looks a little thicker than water because, well… it is!
To make slime, the molecules in the Activator solution “cross-link” (or bond with) the long strands of PVA molecules. Think of the bowl of chains again. What happens if you toss a million tiny magnets into the bowl and stir? This time when you reach in and grab just one chain, they all come out at once. The Activator solution is the “magnet” and it links to water molecules throughout the PVA chains. (NOTE: Activator solution links chemically, not magnetically.) When you try to pull out one PVA chain, all the cross-linked chains come with it. You’ve got slime on your hands!
Part 2 - Deeper into the Science...
This version of slime science is more detailed and science-focused for those who have more time. You should read the shorter version first to get an overview of things.
Polyvinyl alcohol (PVA) liquid is filled with tangled and twisted strands of polymer. Think of a plate of cooked spaghetti. Simply dumped onto a plate, the pasta forms a tangled pile. When stirred with a finger, however, the pieces tend to line up and to “smooth out” a little. With no bonding agent in the mix, stirring the PVA liquid does the same thing and produces a cool, slippery feeling on your finger.
While “smoothing” the polymer by stirring may straighten the PVA a little, a cross-linking agent – the Activator solution – is needed to produce slime. Cross-linking agents are ions that temporarily connect polymer strands using relatively weak ionic bonds. These bonds – usually hydrogen bonding – are strong enough to link the polymer strands together but not strong enough to make the mass a complete solid. They break easily but reform under flow as well. The fact that PVA is so soluble in water may be due to its extensive hydrogen bonding ability.
PVA slime is a non-Newtonian fluid that is dilatant. In other words, it dilates or expands when a force is applied to it. It earned the non-Newtonian label because it doesn’t follow the rules laid down by Sir Isaac Newton. Obedient fluids maintain a constant “viscosity” depending on their composition. (Viscosity is a measurement of the resistance to flow when a strain is produced in the substance by some externally applied force.) Liquid water is always runny and has a low viscosity. Honey is a thick, slow moving liquid with a high viscosity. (Temperature changes can alter both of these viscosities.) Slime’s viscosity can be changed based on the level of a force applied to it. Other thick liquids that have a variable viscosity include ketchup, gelatin, some glues, corn starch in water, quicksand, wet sand on the beach, some printer’s inks, and Silly Putty. If even a small amount of force is applied to slime, like stirring it with a finger, it’s somewhat watery. If a lot of force is applied suddenly, such as hitting it with your hand, the slime briefly becomes a solid as water is pushed aside by the impact and the molecular matrix resists the force. It’s how molecules are bonded in slime that accounts for the interesting results you see.
While the PVA gives slime its foundation, an Activator solution is needed to move it into the non-Newtonian realm. In most PVA slime mixtures, sodium tetraborate is used as the Activator and is about 2% of the final slime. When dissolved in water, it dissociates into sodium ions and borate ions. These ions mix among the polymer chains and form weak ionic bonds between them and the liquid that results is a thicker material: slime! These bonds allow the PVA to stretch and flow when a force is applied to the slime, be it gravity or a smack. The ratio of the polymer to the Activator solution is a factor in the consistency of the finished slime. You can change slime’s texture simply by using more or less Activator solution.
The most abundant material in slime is water. In fact, water is well over 90% of the slime you’re holding. The remaining chemistry is pretty simple. PVA is a long-chain polymer that has a “backbone” of carbon (C) atoms with numerous hydroxyl (OH) groups connected to it. As a result, only about 2% PVA is needed in the mix. The PVA molecule has a structure that’s made by repeating vinyl alcohol monomers.
You know what’s making me lose my mind now? The people who hate Borax. What do you know about Borax? NOTHING!
I’ve been using Borax for almost 30 years to teach kids how to make slime. Borax is the perfect linking agent; Sodium Tetraborate.
Our news stories were totally irresponsible telling people that this is dangerous. It has vilified something that we need to get kids excited about science and I’ll venture to guess, you know nothing about Borax.
Do you know something about Borax?
Borax: Sodium Tetraborate Decahydrate Is the Borate ION, the borate compound that’s the perfect linking agent for slime. Where was it originally discovered? – In Tibet, in evaporate lake beds, these dry lake beds, these salts that they mine, that’s how they originally found Borax.
Now it’s used as a detergent, in cosmetics, it’s actually even used in some food. There are so many uses. Just a quick glance of wikipedia and you’ll find all the natural sources of it, where it comes from and all the things that can be used for.
Now everything is “Borax is bad”. Where did that come from? How did Borax get to be bad?
Well, Borax had to be bad because of an irresponsible article that came out on TV, (I’ll let you figure out who said this) of a mom who allowed a kid to make as much slime as she wanted to for a long period of time. This kid was soaking in borax and water making slime, having fun and what happened? Her hands got irritated… Her skin got irritated… you’d think that would make some sense but no… We’re gonna let her kid continue to play, continue to play until you take her to the hospital, claim that there’s burns on her and now of a sudden, you can’t use Borax.
I wonder what the people from Elmer’s think about us not being able to use Borax. They must have a solution, we gotta find Elmer’s glue!
So, here we go, our kids still want to make slime but “Borax is bad”… Can’t have Borax… Because it burns your hands. it’s horrible! – You couldn’t even find white glue on the store shelves a year ago so I’m sure that they’ve come up with something because this is how you make slime, right?
They’ve come up with the solution, how come I didn’t even think of this 30 years ago… Elmer’s glue + baking soda + Contact lens solution???
That’s the secret! What can be on contact lens solution that would link all those molecules together?
We gotta go find some contact lens solution!
Alright, here’s our contact lens solution. There must be some secret that’s inside so that I don’t have to use the Borax anymore… Let’s take a look… Do you see what it says?
BORIC ACID & SODIUM BORATE… Oh my… There’s Borax in contact lens solution! (Yes, people have been putting Borax in their eyes for ages)
But it’s just fine to use contact lens solution with glue, that’ll make perfect slime because we are chemically illiterate. We have no idea what we are really doing here, so they trick us into thinking everything is fine with this, when in fact we’re still using Borax.
Why is it that major buyers of stores, are banning anything with Borax in it? All the science kits and everything because “borax is bad” yet, it’s ok for another company to say “hey, the safe version” and it goes all over social media… Well that’s chemically illiterate. Completely misses the point that Borate Ions are what link molecules together. What links molecules together gives you slime… Stop being an idiot!
You know what we learned today? Maybe you shouldn’t give your kid a box of Borax and let him/her sit for a couple months and just play with it without being supervised. What else did we learn? We learned that it’s a team effort, if we want to get our kids excited about science and engineering, if we want to prepare them for a STEM based career, if we want teachers to have the tools to get our kids excited about science, to possibly plant a seed and let it sprout, then it might be a good idea to leave it to the people who know something about the science.
Ask some questions before you go typing stuff that you know nothing about and making it really rough for the rest of us… That’s what we learned today.. BORAX IS OK
There are naturally occurring polymers that can produce a true, non-Newtonian slime, e.g. guar gum (taken from guar beans), methylcellulose (taken from plants), milk (taken from cows) and cornstarch (taken from – well, you get the idea). Another favorite is an ordinary glue like Elmer’s® School Glue (either white or clear – both washable). You need to keep in mind that there will be huge differences in consistency and flow between glue slime and PVA slime. But heck, both are true slimes so you might as well explore them!
PVA is used by the plastics industry to form surface coatings and, among other things, to make surface films resistant to gasoline. It’s also used to make artificial sponges, hoses, and printing inks. If you check out the ingredients of contact lens wetting solutions, you may find PVA used as a lubricant and a cleanser. Most PVA solutions contain a special disinfectant to help resist those pesky germs found on those not-so-clean hands of yours, too. PVA is also used as a thickener, stabilizer, and binder in cosmetics, paper cloth, films, cements, and mortars. PVA solution dries to a thin plastic-like film that is finding use in packaging materials. If left in the environment, the PVA film will naturally break down rather than require a major clean-up effort. It’s good stuff!
Since PVA is an excellent cleanser, it can do something that’s a challenge for the glue version. Dip an index finger into the PVA and pick up only a drop. Rub your index finger and thumb together in a circular motion using medium pressure and speed. There are changes to look for in the PVA. At first, it’s slippery but not slimy at all. As you rub, however, it begins to dry out and thicken. As you apply more pressure, the PVA begins to lift dirt and dead skin off your finger and the circular movement gathers it into clumps on your spotless fingertips. When you check again, you’ll have loads of crud piled up. This is what’s called the “Booger Stage” of slime and it’s impressive! It looks like you’ve been nose-mining for hours when all you’ve really done is clean your fingers with PVA. It’s surprising just how much great (and harmless) fun you can have with science!
The information under the A Slimy History and the Slime-Science Basics in Two Parts tabs has been largely all about PVA slime. (You probably know more about it now than you thought possible.) While Steve has always leaned towards PVA slime as the favorite (It’s a first-love thing and he calls it “real” slime.), he has taken on glue slime as a great addition to the Spangler slime family. And why not?! It’s readily available, clean, easy to make, and allows for even more discoveries to be made. (Besides, it’s interesting to note that there are PVA chains in the glue as well.)
Is it a solid? Is it a liquid? Just what is this slick, stringy, rubbery stuff? This variation on PVA slime will probably remind you of a similar material found in many toy stores. Glue slime is the most popular version of “slime” among teachers because it’s so easy to make (with very little messiness) and serves as a great visual tool for introducing students to the properties of polymers. Normally, the glue hardens as water evaporates from it. The result is that two objects are held together tightly. If you can prevent or slow the water from evaporating out of the glue, you get a slime. The Activator solution locks up the water and evaporation drops to a minimum. Eventually, the slime will dry out and the drying process will actually speed up over time.
Clean-up is as easy as making either slime and that’s good because you’ll spend a lot of time playing with… uh, that is, working with the slimes you’ve made. You can store them in a sealed sandwich bag, but eventually you’ll need to toss them into the trash and not down a drain or toilet. However, letting a batch sit in an open dish and totally dry out results in some very interesting slime art. It does takes a long time to dry, however. If you’re really finished, toss it into the trash (not down a drain or a toilet). Your lab equipment can simply be washed in hot, soapy water and kept for future slime discoveries.
Looking for the easiest recipe and the best slime ingredients on the market?
Skip the glue and make PVA slime like the pros!
Easy and safe way for parents and teachers to explore the science of dry ice with fog-filled bubbles!
Try adding these “Special Ingredients” to your Slime that are guaranteed to be a hit at your next party
Add a couple handfuls of styrofoam beads to the PVA solution before you mix in the Borax.
Get that disgusting vomit look! – Grow one or two scoops of Jelly Crystals and add it to the PVA solution before you mix in the Borax.
How about a fancy pearly finish? Just a little squirt of Pearl Swirl in the PVA solution and you’ll have cracked the code to making fanciest slime!
Make it shine! – Add glitter to the PVA solution before you mix in the Borax.
Colorful Eyeball Slime you say? – Grow one or two scoops of Jelly Crystals with your choice of coloring and add it to the PVA solution before you mix in the Borax.
Try mixing party favors such as plastic cockroaches, halloween decorations, and anything else you can imagine for a super spooky batch of slime.
Slime Factory takes the science of making gooey slime to the next level with “mix-in” ingredients that are guaranteed to be a hit at your next party. Attach the hand pump to the one gallon container of Slime Goo and pump the perfect amount into a shaker cup.
THE PERFECT PARTY SLIME! This kit comes with 128 ounces (that’s 1 gallon) of the highest quality PVA (polyvinyl alcohol) solution colored green. Graduate from making the ol’ Elmer’s Glue slime to this amazing slime experience.
When you’re done playing (oops… experimenting) with your slime, combine all of your slime into one giant pile. Find a safe surface (counter top, glass table) where the slime can spread out and dry for 5-7 days. The trick is not to touch the slime while it’s drying. Use a fan to speed up the process. When the water evaporates, your gooey, gooey slime will turn into an amazing piece of science art.