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By Don Riefler, Children's Museum Science Educator and Slime Expert.
You know, I bet some of you think you’re pretty good at slime. And I’m sure some of you are. But I’ve been in the slime game for a long time, and I’ve seen so much slime it’ll make your head spin. I’m practically a Ghostbuster I’ve dealt with so much slime in my day. I remember a day back in 2013 I made over 150 batches of slime in a 2 hour period. Not even exaggerating. People just coming up to my slime table and making more and more and more. Such is the power of slime.
Needless to say, I’ve seen lots of different kinds of slime made with lots of different ingredients. Depending on what you use, textures, colors, and consistency can change, but the underlying chemistry is always the same. In this list of slime, I’ll give you some of my favorite options, all of them safe and easy to do with stuff from the store, then we’ll talk about that chemistry.
Beware, though: I’m not a fan of precise slime ingredient measurement. Experimenting with the amounts of each ingredient until you get the perfect slime for you is half the fun! I’ll tell you what to use, and give you some general guidelines, but for the most part it’s up to you to balance things to your taste. So to speak. Don’t actually eat any of the slime. My mama always said there’s a difference between “non-toxic” and “edible,” and that’s definitely true of slime.
Anyway, slimeheads...
Things you will need for all recipes:
- A decent sized bowl
- A spatula or mixing spoon (silicone if you have it to help avoid sticking)
- Paper towels, soap, and water (for the inevitable clean-up)
- An airtight plastic container to store your finished slime
RECIPE #1: YOUR BASIC SLIME
We have to start somewhere, so let’s start with plain ol’ slime. Nothing fancy here, but it’ll be a good warm-up for what’s coming.
Ingredients:
- 1 bottle plain white school glue (like Elmer’s)
- Baking soda
- Contact lens solution
- Measuring spoon
- Food coloring (optional)
Instructions:
- Empty the entire bottle of glue into your bowl.
- If you want it to be colored, add 3-5 drops of food coloring and mix it in. Don’t use too much or your slime will stain stuff.
- Measure out and add ½ Tbsp. of baking soda. Mix.
- Squirt a little bit of contact lens solution into your bowl. Start mixing.
- As you’re mixing, continually dribble bits of contact lens solution into your mixture until your slime begins to come together into a consistency you like. Be careful, though. Not enough and you’ll just have wet, baking soda-ish glue; too much and it’ll be runny.
- When you get your perfect slime, give it some good solid hand kneading and then it’s time to play!
RECIPE #2: GLITTER SLIME
Okay, so you’ve mastered basic slime and maybe even added a little color. Let’s take it up to the next level by adding some bling.
Ingredients:
- 1 bottle glitter glue
- Baking soda
- Contact lens solution
- Measuring spoon
Instructions:
- Same as before. Whole bottle into bowl.
- ½ Tbsp. of baking soda. Mix.
- Carefully add contact lens solution. Mix.
- Knead.
- Play.
RECIPE #3: STARCH GLITTER SLIME
Good work. You’ve mastered the basics. Now we’re going to switch up a couple of our ingredients. The same underlying chemistry is occurring here, but this change will make it happen a bit differently, giving us slime with a slightly different consistency.
Ingredients:
- 1 bottle glitter glue
- Liquid laundry starch
Instructions:
- This is still slime, so I think you know step 1. Glue + bowl = happiness.
- Splash in a bit of your starch. Start mixing like you did when you added the contact lens solution, adding more slowly until your slime begins to come together.
- When your slime has reached your desired consistency, give it a few good kneads and let it sit for a few minutes.
- Go to town.
RECIPE #4: FLUFFY GLITTER SLIME
Now we’re really going to kick it up a notch. The addition of a crazy new ingredient will makes this unlike any of the other slimes we’ve made so far. You ready for this? I hope so.
Ingredients:
- 1 bottle glitter glue
- Liquid laundry starch
- Water
- Shaving cream (the old foam kind, not the gel kind)
Instructions:
- Glue in bowl. You noticing a pattern yet?
- Add a splash of water to thin out your slime a tiny bit. Mix.
- Add some shaving cream. Use a pretty large amount. By the time you’re done mixing it into your glue, your bowl should look 3-4 times more full than it was before you added the shaving cream.
- Mix extremely well. Do not skimp on the glue and cream mixing!
- Once again, add the starch, first just a bit, and then more bit by bit as the slime begins to come together, stopping once you get to the perfect fluffy slime consistency for your individual fluffy slime needs.
- Enjoy!
RECIPE #5: STRAIGHT UP ECTOPLASM
Okay, here we go. This time we get to break some stuff before we make our slime. Well, sort of, anyway. We’re going to combine a totally different type of science with our slime chemistry and come up with something sure to impress all of your friends and (if used right) make for the perfect Dr. Venkman (or Dr. Holtzmann) cosplay. And don’t worry. I’ll explain how our second science works, too.
Ingredients:
- Plain white glue (it’s back!)
- Liquid laundry starch OR baking soda/measuring spoon/contact lens solution (dealer’s choice)
- A yellow highlighter marker
- Food coloring
- A large knife (optional, and serrated works best)
- A cutting board (if you end up needing the knife)
- A grown-up in safety glasses
- Any UV flashlight (here’s a good, cheap option, but you can usually find some kind of UV/blacklight at most regular big-box stores for a few bucks)
Instructions:
- Do I even have to say it?
- Okay, fine. Put all the glue in the bowl. I have to do all the work around here.
- Put in 2-3 drops of your desired food coloring. Mix.
- Here’s where it gets a bit dicey. We want to get to that sweet, sweet highlighter ink inside that fluorescent marker. Some highlighters can be taken apart by hand, so try for one of those if you can find them. If not…
- Remove the cap from the highlighter.
- Ask your grown-up in safety glasses to please take the knife, the highlighter, and the cutting board.
- Go into another room and yell for them to please use the knife to cut off the top of the highlighter about an inch down from the tip. Done safely, pieces shouldn’t fly around, but your grown-up is in safety glasses just in case. When this step is done properly, the tube that contains the marker’s fluorescent ink should just fall right out.
- Once your grown-up in safety glasses has put the knife away, come back into the room and pick up that tube full of ink. You’ll see that it’s a plastic tube open on both ends, like a straw, filled with a material that is absolutely soaked in yellow fluorescent ink.
- Squeeze a bunch of that ink into your slime. Mix. You will get ink all over your fingers, but that’s cool. It’ll wash off.
- At long last, the final step draws nigh. Depending on your slime preference, add and mix your starch or your baking soda/contact lens solution. Finish whipping up your slime.
“What’s the deal?” You may be asking me now. “It’s just the same old slime with a slightly yellow tinge thanks to the ink you made me get all over my fingers!” Not so fast, my friend. That’s special ink. Which brings us to step 11... - Take your UV flashlight and go to a dark room. Turn off all the lights. Hold your slime in your most creepiest, ghostliest fashion in one hand and shine your UV light onto it with the other.
- Marvel at the wonder of glowing slime!
THE SCIENCE
Here’s the main thing: all slimes, no matter what recipe you’re using, are made up of a chemical structure called a polymer. We can break down “polymer” into its root words, both from Ancient Greek, to figure out what it means. “Poly” means “many” and “mer” (from “meros”) means part, so a polymer is a molecule (a chemical combination of multiple different atoms) made of many smaller parts all linked together. Polymers are typically stretchy, or at the very least can be molded easily when they’re heated, and then set into a stable shape when they cool down. Rubber, plastic, elastic, and PVC are all common examples of polymers. Heck, even your DNA is technically a type of polymer.
Glue, on its own, is not a polymer, but is has the potential to be one. It is a solution of monomers. “Mono” means “single,” so “monomer” means “single part.” If you can find a way to combine those single parts, you can turn them into a polymer. That’s what the baking soda/contact lens solution and the liquid laundry starch do. They are called crosslinkers. A crosslinker has the power to combine those monomers into polymers. This is a form of chemical change: you start with one set of molecules (our glue monomers) and end with a different set (our slime polymer). What we finish with is chemically different from what we started with.
All of our slimes work on that same basic principle of crosslinking monomers into polymers. When we add different ingredients, we add different qualities to our slime, but the chemistry is the same. Glitter slime is a polymer with glitter in the mix that makes it shiny. The shaving cream that we added to fluffy slime hangs out in the mixture and does what foam does: holds on to tiny little air bubbles, which is what gives that slime its extra size and its soft, fluffy texture.
Now where the science gets more interesting, like I said above, is when we add that highlighter ink. Like glitter and shaving cream, it doesn’t change the crosslinking reaction, but it brings a very special quality to the slime mixture: fluorescence.
Fluorescence is a property of certain materials to absorb light and then release it back with slightly less energy than it had when it came in. Fluorescent markers are always doing this whenever they’re exposed to light, but you can’t really tell except for that slight difference that makes you know you’re looking at a neon marker and not a regular one. Where fluorescence really shines (get it?) is when you use light with more energy than the light that is visible to humans: ultraviolet (UV) light. This is gonna get a little complicated and quantum but it’s super cool.
We can’t see UV, but some birds and insects can. It’s all around us, coming from the sun just like visible light, and in addition to being invisible to our eyes, it’s packed with more energy than visible light. A UV flashlight puts out UV light with just a tiny bit of light that we can see. When you shine it onto a fluorescent material, the molecules that make up that material absorb its energy. This extra energy causes their electrons (tiny parts of atoms that orbit around an atom’s central nucleus) to jump higher in their orbits, just a tiny bit farther away from the nucleus, into a different energy shell. They can’t hold onto that new energy or their new orbits forever, though, really just for a split second, and so they fall back down to their original orbits (what we call their ground state) and release the extra energy as they do so.
Here’s the thing, though. They had to use up a tiny bit of that energy they got from the UV light to jump up into a higher electron shell in the first place, so what they end up releasing is not quite as energetic as the UV that they absorbed. What’s got less energy than invisible UV light? Plain old visible light. You shine UV onto fluorescent marker ink in a dark room and it will glow like a firefly as long the UV is touching it. Add that into the mix of a sweet polymer slime and you have something truly cool to use next Halloween.
FINAL WORDS
Now that you understand the basics of slime making and crosslinking, you can experiment with the ingredients we’ve used here, and maybe even try others. You always need your glue and your favorite cross-linker, but what else can you do? Can you make glowing foamy slime? What happens when you mix in something weird, like sand? Can you use it to build a slimy sand castle? The possibilities are endless, and it just takes some creativity and a little bit of time.
Remember, no matter what kind of slime you make, always clean up after yourself, and always put your slime away in an airtight container in the fridge when you’re done playing. Homemade slime doesn’t last as long as natural polymers like rubber or manufactured polymers like plastic, and, like food, it’ll stay fresh longer if it’s sealed up and kept cold.
But even though we’re storing it in the refrigerator, you’re still not allowed to eat it. Cool? Cool. Now get out there and make some slime!
