Here at Slime Obsidian, we've made and sent millions of slimes since 2017, and almost every one of them started the way yours will: with glue, an activator and a bowl. In this guide we'll explain what's actually happening in that bowl, give you the starter recipe we'd hand any first-time maker, and walk through the reasons a first batch goes wrong, so yours doesn't.
What slime is
Slime is glue that has been taught to hold together.
School glue is made of PVA, long chain-like molecules floating in water. On their own they slide past each other, which is why glue pours. An activator, most often borax dissolved in water, links those chains to one another at points along their length. Link enough of them and the glue stops behaving like a liquid and starts behaving like slime: it stretches, holds a shape for a moment, then slowly gives way.
That one idea explains almost everything about slime:
- Too few links and it stays sticky and wet.
- Too many and it turns stiff and rubbery, and snaps instead of stretching.
- The water inside is what keeps it soft, which is why slime left open dries out.
Every texture you have ever played with, from glossy and clear to thick and buttery, is this same network with something changed: the glue, how far it is activated, or what gets folded into it.
The ingredients and what each one does
- Glue is the body of the slime. White school glue makes an opaque slime that takes color softly. Clear glue makes a glassy one.
- Activator decides the texture's strength. It is the one ingredient you add slowly, because it is much easier to add than to take away.
- Water, in the activator and in the glue, is what keeps a slime soft and stretchy.
- Texture builders change how the slime feels: clay for softness, foam for fluff, lotion and glycerin for a smoother stretch.
- Add-ins change how it sounds and looks: beads for crunch, sprinkles and charms for decoration.
- Color and scent go in last, or at least before the activator, and in small amounts. A little goes further than you'd expect.
Your first slime: the starter recipe
This is the simplest slime there is: just glue and activator. It's the base under almost everything we make, and it's where we tell every beginner to start, because it's the best way to learn what activating feels like.
You'll need
- 1 cup white school glue
- 1 tablespoon borax
- 1 cup warm water
- A bowl, a spoon, a measuring spoon and an airtight tub
Make the activator. Stir the borax into the warm water until it dissolves completely and the water is clear. We always recommend an adult handles the borax. Label the container, and keep what you don't use for your next batch.
Make the slime
- Pour the glue into the bowl.
- Add half a tablespoon of activator and stir well.
- Keep adding activator half a tablespoon at a time, stirring after each, until the slime pulls away from the sides of the bowl. Most batches need 2 to 3 tablespoons in all.
- Take it out and knead it. It will feel sticky at first. That's normal. Knead for a minute or two before you decide it needs more activator.
- If it is still sticky after kneading, add a few drops more and knead again.
- Store it in an airtight tub. It keeps settling for a few hours after you make it.
One cup of glue makes about enough to fill an 8 oz tub.
Why first batches fail
Almost every slime that goes wrong goes wrong in one of a handful of ways.
- Rushing the activator. Adding a lot at once over-links the glue, and the slime turns hard and rubbery. Small amounts, with stirring in between, is the whole technique.
- Stopping too early. Freshly activated slime is always sticky. Kneading is part of activating, so give it time before adding more.
- Warm hands and warm rooms. Heat softens slime. A slime that seems sticky in your hands may be fine once it cools.
- Measuring by eye. Slime is chemistry. The same glue and the same activator in slightly different amounts give a different slime.
- The wrong glue. Slime needs a PVA glue. Glue sticks and many craft glues won't activate the same way.
None of this is a reason to worry. Our founder, Jacob, made every one of these mistakes himself when he started Slime Obsidian. It's simply the part of making slime that takes practice, and the part a tested formula takes care of for you. Here's why making slime is easier than it looks.
From a starter to a texture
Once you can make the starter, every other slime is a set of choices made on top of it:
- The glue: white for soft and opaque, clear for glassy.
- How far you activate it: looser for a glossy pull, firmer for a slime that holds its shape.
- What builds the texture: clay, foam, lotion, or nothing at all.
- The add-ins: for sound, for crunch, for looks.
- Color and scent: the part that makes it yours.
How those choices come together for each texture is where slime-making becomes a craft. The Slime Texture Field Guide shows what each texture is and how to tell them apart.
Safety basics
- Slime is for hands, never mouths. Wash your hands after playing.
- An adult should handle the borax and the activator, and store them out of reach.
- Stop if your skin feels irritated.
- Keep slime off carpet, couches and clothes.
As every one of our jars has always said: Slime is not edible and should not be played with by children under the age of 7 or without adult supervision.
Frequently asked questions
Can I make slime without borax? Yes. Contact lens solution with baking soda is the most common alternative. It works on the same principle, linking the glue, and gives a slightly different feel.
Why is my slime sticky? It is usually under-activated, still warm, or hasn't been kneaded long enough. Knead first, then add activator a few drops at a time.
Why is my slime hard and rubbery? Too much activator, usually added too fast. Next time, add it half a tablespoon at a time.
How long does homemade slime last? Stored airtight and away from heat, for a long time. How to store slime and keep it from drying out covers it.
How long does it take to make slime? Minutes. Most of it is kneading.
Where to go from here
The starter is the easy part. The textures people fall for, the frostings and clouds and crunches, are where the details decide everything: which ingredients, exactly how much, in what order, and when to stop.
That's what we built The Lab for. Every Friday we drop a new formula, with every ingredient, exact measurements, where to buy them and a step-by-step video of Jacob making it from start to finish. Our School lessons, from The Anatomy of Slime to Slime Care 101, cover the rest. Step inside The Lab.