If you find yourself scratching your head with the latest slime obsession, keep in mind that making slime is actually science! Slime is chemistry! Polymers and Non-newtonian fluids can be a little confusing for young kids, but our short lesson in the science of slime is a perfect way to introduce the science behind the slime to your kids. We LOVE homemade slime!

Polymers and Non-newtonian fluids can be a little confusing for young kids, but our short lesson in basic slime science is a perfect way to introduce the science behind the slime to your kids. We LOVE homemade slime.


Making slime has proven to be extremely fascinating for kids and adults of all ages, but you might not be familiar with the basic slime science. This is great to share with kids who love slime because it’s an awesome learning opportunity already built into an incredibly fun hands-on activity.

First off, have you ever made a really good homemade slime with your kids? If you haven’t (or even if you have), make sure to check out our collection of the BEST HOMEMADE SLIME RECIPES.  We actually have 5 basic slime recipes which are the foundation for all our slime variations.

The following slime video uses our very popular saline solution slime recipe.  Make sure to check out more  slime recipe videos.

No more having to print out a WHOLE blog post for just one recipe!

Get our basic slime recipes in an easy to print format so you can knock out the activities!



Slime science starts with the best slime ingredients including the right kind of glue and the right slime activators. You can see all our recommended slime making supplies here. The best glue is a PVA (polyvinyl- acetate) washable school glue.

You have several slime activators to choose from (all in the boron family). These include saline solution, liquid starch, and borax powder, and all contain similar chemicals for making a slime substance. Cross-linking is what happens when the glue and activator are combined!


slime ingredients


Slime involves chemistry!  Chemistry is all about states of matter including liquids, solids, and gases. It is all about the way different materials are put together, and how they are made up of atoms and molecules. Additionally, chemistry is how these materials act under different conditions.

Slime is a non-Newtonian fluid. A non-Newtonian fluid is neither a liquid nor a solid. It can be picked up like a solid, but it also will ooze like a liquid.  Slime does not have its own shape.   You will notice your slime change its shape to fill whatever container it’s placed in.  However, it can also be bounced like a ball because of its elasticity.

Pull the slime slowly and it flows more freely. If you pull it quickly, the slime will break off more easily because you are breaking apart the chemical bonds.


Slime is all about polymers! A polymer is made up of very large chains of molecules. The glue used in slime is made up of long chains of polyvinyl acetate molecules (that’s why we recommend PVA glue). These chains slide past one another fairly easily which keeps the glue flowing.

Chemical bonds are formed when you mix the PVA glue and slime activator together.  Slime activators (borax, saline solution, or liquid starch) change the position of the molecules in the glue in a process called cross-linking!  A chemical reaction occurs between the glue and the borate ions, and slime is the new substance formed.

Instead of flowing freely as before, the molecules in the slime have become tangled and create what is slime. Think wet, freshly cooked spaghetti versus leftover cooked spaghetti! Cross-linking changes the viscosity or flow of the new substance.


You can experiment with the viscosity or thickness of slime using our basic slime recipes. Can you change the viscosity of slime with the amount of slime activator you use? We show you how to set up your own slime science experiments in the link below.


slime science


Concerned that borax is not good for you?  We have a number of taste safe borax free slime recipes for you to try.  Find out what fun substitutes for borax you can make slime with!  Please note, that a borax free slime will not have the same texture or stretch as traditional slime.


Borax free slime? You bet! Can you still enjoy making homemade slime without using borax, boric acid, or sodium borate? Yes you can! If you are looking for some fun alternative slime making ideas, look no further. We have removed and replaced the classic slime activators with gelatin, fiber, marshmallows, and more to create fun slimy recipes. 


Feel like you are juggling between helping a few students and groups that finish at different times?

Want to know what to say when children ask those difficult to explain WHY questions?


24 pages of AWESOME slime science activities, resources, and printable worksheets for you!! 

When it comes to doing science every week, your class will cheer!



  1. For your information, Slime is created when PVA, in other words Polyvinyl acetate, comes in contact with sodium borate, sodium tetraborate, or disodium tetraborate. Slime is a very easy craft that me and my class love so much, that we make it every Monday! We recommend the following slimes: Floam slime, Fluffy slime, Iceburg slime, Crystal clear slime, and Bubble Rap slime.

  2. We use the box of McCormick liquid food coloring bottles from the spices section of the grocery store!

  3. HI,
    I’m concerned that borax is not good for you. Does the borax react with the PVA to make it less dangerous?

  4. Have you checked out Steve Spangler? He has a great video or two on Facebook regarding the safety of borax powder for slime making.

  5. Why when you add too much borax, the slime becomes stiff? Can u reply ASAP! thank you! 🙂

  6. there are two different types of borax. one is detergent, and one is to kill insects. the detergent is safe, but NOT the killer one

  7. Actually boric acid which is in the same boron family as borax powder is what is used in insecticides as well as eye drops. Borax powder is laundry, some hand soaps and trace in fertilizer since it is mined through the ground. Through an intense processing borax powder can be turned into boric acid. They are however, not exactly the same.

  8. tried different versions of your recipes, with the saline solution we had at home, and the result is too liquid every time… do all saline solutions contain sodium borate? the label on my saline solution does not mention it, therefore I wonder if that isn’t the reason why it doesn’t work. is there something else I can use instead? i was hoping to avoid borax

  9. Yes, your saline needs the ingredients boric acid and sodium borate to work properly. Depending on your location, you can also try liquid starch.

  10. slime is amazing you can do anything with it like: Put it in stress balls, or play with it with your hands. Also, it’s a great stress reliever I do recommend this. Thx for the recipes 😀

  11. Hi there- I want to use your liquid starch slime recipe for my first grade Halloween party–Can you tell me if one recipe is for one kid or for how many—so for a class of 24- do I make 24 recipes?


  12. Hi! One recipe will make quite a bit of slime. One batch could easily be split 3-5 ways depending on how much you want each kid to end up having. I like the condiment size containers that hold about 2oz each! One batch usually fills about 5 of those! Feel free to email me [email protected] if you would like to talk about it more!

  13. As someone who’s read about and experienced PVA and borax together I would say that you should probably stay away from it. I know that there were many reports on the news about kids getting burns from the borax in their slime. Personally I did not get burned but my hands did feel tingly and slightly hot. All in all it does work as an activator but I would advise to choose another activator like detergent or contact lenses solution.

  14. Sensitivity is a huge issue. However, my skin did not like laundry detergent at all and I highly advise to stay away from laundry detergent which is why we do not have a recipe for it. We use less borax than most recipes, and if you do have sensitive skin I would choose saline solution (not contact lens solution). Liquid starch is another choice. All the choices contain some form of borons.

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