Contact lens solution containing boric acid makes a good Borax substitute for making slime, when combined with baking soda and glue. (Note: Most liquid laundry detergents in recipes for “Borax-free” slime contain Borax.)

What’s the science behind the fun? To make slime, you need a chemical called a crosslinker to make all of the glue molecules stick together. When you use contact lens solution, the boric acid in contact solution combines with baking soda to make borate, the same crosslinking solution that Borax contains.

To make Borax powder-free slime, just add a pinch or two of baking soda per ounce of glue (around 1 tsp per bottle of clear glue), stir, add food coloring or glitter and then keep adding contact lens solution and stirring until the glue isn’t sticky any more. You can add water to the glue before adding the contact solution to change the consistency of the slime.

You can find more slime recipes here.

A homemade slime craze is sweeping the nation, and glue is becoming a limited resource as stores are swarmed by school kids on a quest to make the perfect goo.

from Kitchen Science Lab for Kids (Quarry Books 2014)

I’ve posted recipes and videos for slime-making on this website and included one in “Kitchen Science Lab for Kids.” For my most recent book, “Outdoor Science Lab for Kids,”  I invented a recipe for making slime that oozes from a bottle like a living thing.

From “Outdoor Science Lab for Kids” (Quarry Books 2016)

But the other day, my 11-YO brought home a slime recipe featuring clear glue, baking soda, shaving cream and contact lens solution, and I was baffled. Which ingredient was the cross-linking chemical that would bind all of the glue molecules together into slime? I hadn’t had much luck using any cross-linker besides Borax laundry detergent.

Curiosity got the best of me, and a trip to Walgreens confirmed my suspicion that most contact lens solution contains boric acid, a cross-linking chemical related to Borax. In the glue aisle, I discovered a “Borax-free slime” recipe for slime made with Tide Free and Gentle. (Tide detergent does, in fact, contain the same chemical in Borax, so it’s not really Borax-free.)

A few days later, a friend called saying that the slime her kids were making with Borax and clear glue wasn’t turning out. That’s when I decided it was time for us to do some scientific sleuthing.

From Kitchen Science Lab for Kids (Quarry Books 2014)

We tested two glues (clear glue and white school glue) with three cross-linking solutions (Borax laundry detergent, contact lens solution, and Tide Free and Gentle (which contains some Borax) to see how the end-products would differ.

Helpful hints: A bottle of glue contains 4 or 5 oz, which is a little more than half a cup. Mix glue with other ingredients BEFORE adding the cross-linker.  Keep slime away from toddlers, as ingredients may be harmful if consumed. Always wash your hands after playing with slime.

Here’s what we found:

Traditional Borax Slime: Add equal parts glue and water (for example, one 5 oz bottle of glue+5 oz water.) Add glitter or food coloring. Dissolve a few spoonfuls of Borax in a cup of water to make a Borax solution. Add Borax solution to glue, a little at a time, until it no longer feels sticky. 

-White school glue works best for this recipe and the result is smooth slime that can be rolled into long snakes.

-Clear glue doesn’t work well with this recipe and produces brittle slime. Save clear glue for the two recipes below. 

Puffy Slime: Add 5 oz glue to a large bowl. Stir in 1/2 tsp baking soda, 1/4 cup shaving cream and glitter or food coloring. Mix well. Add contact lens solution as a crosslinker and stir. Keep adding contact lens solution until your slime is no longer sticky and knead slime until it has the desired consistency. 

-White school glue works well with this recipe and results in a puffier, firmer product than clear glue. The slime has a strong shaving cream smell. 

-Clear glue works well for this project and produces nice, smooth puffy slime that smells like shaving cream.

Tide Detergent Slime: Add 5 oz glue to a large bowl. Stir in 5 oz water and some glitter or food coloring. Add 1/4 cup of Tide Free and Clear laundry detergent. Mix well with a spoon and then hands to the desired consistency. 

-White school glue works well with this recipe and the soap in the detergent makes tiny bubbles in the slime. 

-Clear glue works well for this project and makes great , smooth slime that’s puffy from the soap in the detergent.

Try adding cornstarch, lotion, or anything else you can think of to perfect your recipe.

What are you waiting for? Go make some slime!

The Science Behind the Fun: A polymer is a long chain of repeating molecules, kind of like a string of pearls. The polymer in school glue is called polyvinyl acetate. Borax solution (sodium tetraborate) and boric acid (combined with baking soda to make borate), are cross-linking substances that make the polymer chains in glue stick together.  As more and more chains stick together, they can’t move around and the solution gets thicker and thicker.  Eventually, all the chains are bound together and no more Borax or boric acid solution can be incorporated into the slime.

Buying gifts is fine, but it’s more fun to make them. This year, we decided to make botanical gifts for the adults on our list, and slime kits for the kids.

To make a slime kit, you’ll need:
-glue
-glitter glue (optional)
-Borax laundry detergent
-small plastic sample cups or paper cups (optional)
-food coloring
-jars with lids
-a small plastic bin or shoe box
-plastic spoons
-extra glitter (optional)

Label the jars and fill as follows:

1. Bouncy Ball Mix (fill with glue)
2. Slime Mix (fill with equal parts glue and water, mixed well)
3. Borax detergent (fill with powdered detergent)
4. Cross-Linking Solution (leave empty)
5. optional-Sparkly Bouncy Ball mix (fill with glitter glue)
6. optional-Sparkly Slime Mix (fill with equal parts water and glitter glue, mixed well)

Make an instruction sheet for the kit. (Print out the info below, or copy it onto a card.)

To make slime:

1. Fill Cross-Linking Solution container with warm water. Add about 2 tsp Borax per 1/2 cup water to the container. Mix well. (Don’t worry if all the Borax doesn’t dissolve!)
2. Add a few spoonfuls of Ball Mix or Slime Mix to a small plastic cup or paper cup.
3. Add a drop or two of food coloring to the cup. Stir.
4. Add 3 spoonfuls of the Cross-Linking Solution to your ball mix or slime mix and stir well.
5. If the slime still feels too sticky, add a little more Cross-Linking Solution.
6. Remove your completed slime from the cup.

The Science Behind the Fun:

Glue is a polymer, which is a long chain of molecules linked together, like a chemical chain.  The polymer formed by water and glue is called polyvinyl acetate.

The Borax solution is called a cross-linking substance, and it makes the glue polymer chains stick to each other. Eventually, all the chains are bound together and no more cross-linking solution can be taken up.

To finish the slime kit, fill the plastic bin with the ingredients you put together, including jars of ingredients, instructions, plastic spoons, and mixing cups (optional.)

Slime from Kitchen Science Lab for Kids (Quarry Books)

Combine science and art in this awesome experiment!

You’ll need 8 oz water bottles, glue, Borax detergent, baking soda and vinegar.

First, decorate full 8 oz water bottles with tape, marbles and whatever else you can find.

Then, follow these directions to make foaming slime ooze out of their heads, using a simple chemical reaction! You’ll love it!

We supersized the foaming slime experiment from Outdoor Science Lab for Kids to make a giant foaming slime volcano. And it was awesome!

When I do science outreach with kids, I encourage them to get creative and try different ratios of ingredients in experiments like Mad Scientist’s Green Slime, to see how their results will vary. Will they get stretchy goo, or bouncy balls?

Foaming Slime Monster- KitchenPantryScientist.com

This morning, I decided to explore the kid in me and see what fun new experiment I could come up with, using the ingredients for polymer slime. After lots of giant failures, I came up with a fun way to combine two experiments: Mad Scientist’s Green Slime and Paper Bag Volcano. My kids gave it a big thumbs up and gave the experiment a fun name. Hope you like it too!

For this experiment, you’ll need: Borax laundry detergent (powder), baking soda, glue, vinegar and a full small 8oz plastic water bottle.

1. Remove the label from the bottle, take the lid off and pour out about 2oz of water.

2. Add 1 tsp. Borax and 5 tsp. baking soda to the water in the bottle (we used a paper funnel.) Put lid back on and shake well. Label bottle Borax/Baking soda.

3. Mix together 2 Tbs. vinegar, 2 generous Tbs. glue and a few drops of food coloring. Mix well and transfer to a pouring container, like a paper cup with one side pinched into a spout.

4. Shake the bottle of Borax/Baking soda solution up again and set it in a large bowl. Remove the lid from the bottle.

5. Pour the glue/vinegar solution into the water bottle very quickly, all at once.

6. When your bottle has stopped “erupting,” squeeze the foamy slime out of the bottle into the bowl and mush it all together.

7. Enjoy your foaming slime monster! What would happen if you added glitter? Does the amount of glue you added make a difference? What if you added more?

The science behind the fun: Polymers are long chains of molecules, like a long string of beads on a necklace. In fact, polymer means “many pieces!” Glue contains a chemical called polyvinyl acetate, a polymer that is runny when you mix it with water or vinegar. However, if you add Borax detergent, a crosslinker,  it makes all of the glue molecules stick (or link) together in a big glob.

When you mix together baking soda (sodium bicarbonate) and vinegar (acetic acid), you’re doing a chemical reaction. One of the products of this reaction is carbon dioxide gas.

In this experiment, when we pour the glue/vinegar into the baking soda/Borax solution, we mix baking soda and vinegar at the same time as we link glue molecules together, trapping gas bubbles inside our gluey polymer slime. Your “slime monster” escapes as the slimy bubbles push their way out of the bottle under increasing pressure.

Feel free to share this experiments with your friends. If you’re sharing it on a website, please link back to this post though, since it’s an original experiment! 

If I give you glue, water and Borax, can you come up with a recipe for perfect polymer slime based solely on what you know about the science?

Last week, I did hands-on science with 150 third graders at Success Beyond the Classroom’s Creativity Festival at the University of Minnesota. As they came into the room, I asked them to draw a picture on chalkboard of anything related to science. They drew test tubes, trees, volcanoes, and even scientists!

Then we dug into the science. After doing my favorite large group hands-on experiment with purple cabbage juice to warm them up, I announced that we’d be making polymer slime, but that they would have to invent the recipe for the perfect goo.

To begin with, I talked about the science. We learned that one ingredient in the slime is glue (polyvinyl acetate), which is a polymer, or long chain of molecules. Then, we talked about the fact that adding water to the glue makes it less viscous, or thick. As usual, I had them repeat the vocabulary after me. Finally, I explained that the sodium tetraborate in Borax laundry detergent is a cross-linking substance that makes glue molecules stick together, and that we’d mixed up some Borax and water for them to use as a crosslinker for the slime.

Their challenge was to come up with one “recipe” to make a gooey, soft slime and a second recipe for a harder, rubber-like slime that could be rolled into bouncy balls. They each had a note card and pencil to keep track of their work, plastic teaspoons as measuring tools and paper cups for mixing slime. First, they’d stir up different proportions of glue and water, and then they’d add the Borax solution as a cross linker and mix it all together with a popsicle stick. To make it a little more colorful, they could add a drop of food coloring or some cabbage juice.

Needless to say, there were failures and successes and the kids had a blast.  We talked about the fact that experiments often don’t work on the first try, and each kid explained to the group how they’d made their perfect slime as they demonstrated how it bounced and stretched.

Try it!

What could be more fun than creating your own green slime ?  It’s easy to synthesize your own green goo using only Elmer’s glue (the non-washable kind), Borax (found in the laundry detergent section of Target and some grocery stores), green food coloring and water.

Mix together about 1/3 cup glue and 1/3 cup water with a spoon or Popsicle stick.  These measurements don’t have to be exact.  Add a few drops of green food coloring and stir.

To make the Borax solution, add around a cup of water to a jar.  To the water, add about a Tablespoon of Borax.  Shake or stir to dissolve as much of the Borax as possible.  You’re making a saturated solution, so it may not all dissolve!

Here’s the fun part: Add a teaspoon at a time of the Borax solution to the glue/water mix.  After each addition,  stir the mixture.  You’ll see long strings begin to form and stick together.  Keep adding Borax until the mixture doesn’t feel sticky.  It will form a shiny playdough-like substance.  If you add too much Borax solution, it will feel wet, but you should be able to squish it around in your hands to absorb the extra water!  The slime isn’t toxic, but Borax is soap, so don’t eat it!

What happens? Mixing Elmer’s glue with water forms a substance called a polymer, which is a long chain of molecules, sort of like a string of pearls.  (A molecule is the smallest amount of a specific chemical substance that can exist alone, like H2O, a single water molecule).  The polymer in school glue is called polyvinyl acetate.

The Borax solution (sodium tetraborate) is a cross-linking substance that makes the polymer chains stick together.  As more and more chains stick together, they can’t move around and the goo gets thicker and thicker.  Eventually, all the chains are bound together and no more Borax solution can be incorporated.

You can store the slime in plastic bags.  If you want to make a larger batch, just remember to mix equal amounts of glue and water and then add as much Borax solution as needed.

What could be more fun than creating your own green slime to play with?  It’s easy to synthesize your own green goo using only Elmer’s glue (the non-washable kind), Borax (found in the laundry detergent section of most stores), green food coloring and water. 

In a bowl, have your child mix together about 1/3 cup glue and 1/3 cup water with a spoon or Popsicle stick.  These measurements don’t have to be exact.  Add a few drops of green food coloring and mix well. 

To make the Borax solution, add around a cup of water to a jar.  To the water, add about a Tablespoon of Borax.  Have your child shake the jar to dissolve as much of the Borax as possible.  You are making what is called a saturated solution, so it may not all dissolve!  Don’t worry, it will work just fine.

Have your child add about a teaspoon at a time of the Borax solution to the glue/water mix.  After each addition, have them stir the mixture together.  You should see long strings begin to form and stick together.  Keep adding Borax until the mixture doesn’t feel gluey any more.  It will form sort of a shiny playdough-like substance.  If you add too much Borax solution, it will feel wet.  You should be able to just knead it a little to absorb the extra water!  The slime is not toxic, but Borax is soap, so don’t let your kids eat it!

I am a biologist and not a chemist, but here is the science, as I understand it. 

Mixing Elmer’s glue with water forms a substance called a polymer, which is a long chain of molecules.  (A molecule is the smallest amount of a specific chemical substance that can exist alone, like H2O, a single water molecule).  The polymer formed by water and glue is called polyvinyl acetate. 

The Borax solution (sodium tetraborate) is a cross-linking substance that makes the polymer chains stick together.  As more and more chains stick together, they can’t move around and the goo gets thicker and thicker.  Eventually, all the chains are bound together and no more Borax solution can be incorporated.

You can store the slime in plastic bags.  If you want to make a larger batch, just remember to mix equal amounts of glue and water and add as much Borax solution as needed. 

To make your child feel like a “real” scientist, find an old, button up shirt for your child to use as his or her “lab coat”.  It’s fun and will protect their clothes.  You could even try to find some old safety goggles in your garage for your child to wear, although the ingredients for this project are relatively safe.  (Very young children should always be supervised while doing science projects.)

Have fun!