We’ve discovered a world exclusive secret ingredient to make perfect strong, stretchy, crackle slime every time. Here’s our recipe which uses white PVA glue, colouring, a borax activator and the secret ingredient!

Read on to see how we did it, there’s a video to watch too, plus, of course…..find out the secret ingredient!!

This slime is easy to make!

Here at Devon Science we help kids make a lot of slime, be it a school workshop, a fun community event or a birthday party, we have literally made 1000s of pots of slime with kids. I (chief scientist at Devon Science) experiment a fair amount with different slime recipes and so I decided to try adding a new, secret ingredient – a chemical I had in the lab, one that I thought might just work….and YES! ….it produced as super strong, long lasting, stretchy & soft slime.
My secret ingredient is….POLYOX, or polyethylene oxide.
It sounds very science-y, but it is easy to get. We use it because it turns very gloopy in water and is good to demonstrate self-siphoning liquids. I was so glad I tried it out as it makes the slime really strong – it stretches without breaking, it make bubbles effortlessly and is guaranteed to crackle!

Materials used

Large bowl and something to stir with
PVA glue (see Lab Notes below)
Colouring (food colouring or craft paint work fine)
Activator – I use my home-made borax solution (see Lab Notes below)
The secret ingredient – Polyox (polyethylene oxide)
Measuring spoon
Covering for table
Tub to store slime

Here are the main materials/ingredients we used:


Our method

I poured about 200ml of PVA glue into the bowl.

Then in went a few drops of food colouring and I stirred this in.

Next, I added a dessert spoon of our secret ingredient, Polyox, and stirred this in for 5 minutes until it was completely dissolved.

Finally I added the Activator (borax – see Lab Notes below), a little at a time with good stirring in-between.

Once the slime started to pull away from the sides of the bowl, I knew it is ready to be kneaded in my hands. This is the messy part but you really need to feel the slime to determine if you need to add some more activator. If it feels too sticky, add a squirt of Activator. I kept kneading and squidging, and adding more Activator, until it was perfectly soft and stretchy.


Watch the video to see how easy it is to make:



This slime is very strong and resilient, but doesn’t lose its softness. I can pull and stretch it without it breaking, yet it feels soft and pliable. It’s long lasting too (we’re storing it in an air-tight container).


Bubbles are easy to make and hence it has brilliant crackling properties.  We made this huge bubble outside which was fun!


Lab notes

UK vs USA Slime
American videos on slime making make it so confusing if you’re new to slime, because they use ingredients we’ve not heard of but are readily available over there (e.g. Elmer’s Glue, Tide or Mule Borax). You can buy these items online, but they are expensive and you don’t need to bother as we have everything you need for sliming here in the UK !

PVA glue
Not all PVA glues work, avoid the ones in the DIY section, go for craft PVA glue. We’ve had success with craft glue from the well known UK shops, The Works and Baker Ross.

We make our own Activator using borax. We make a weak solution 2.5% borax which is safe to use.

Borax’s scientific name is sodium tetraborate and nothing works better or is as cost effective as a solution of sodium tetraborate, and so we avoid the alternatives. For example, some recipes suggest using contact lens cleaner that contains boric acid or sodium borate (these contact lens cleaner are sometimes referred to as just “saline”), some say use a starch solution, the kind for spraying on shirts when you’re ironing them, again it needs to contain boric acid or sodium borate.


You may also have heard about safety concerns about borax? Well, if you want to use and make your own borax solution, it’s down to you to get informed about the safety issues and make a decision based on the evidence. In the UK the raw material (sodium tetraborate) is classified as TOXIC, but a weak solution like the one we use, e.g. 2.5%, is of low hazard. We wear Personal Protective Equipment when making up a solution of sodium tetraborate, and we make it up away from other people. We keep the raw material out of reach of children and pregnant women. In case you were wondering, in America borax is readily available to buy in shops as a laundry supplement as it’s not classified as toxic over there!

Want more slime recipes?


Colour-changing thermochromic slime
Magnetic slime
Fluorescent/Hallowe’en slime
Fluffy slime


If you tackle this activity at home you do so at your own risk. If you have as much fun as we did, feel free to share your pictures with us on Facebook.

Have fun sliming!
Bye for now


Chief Scientist at Devon Science

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