Good slime doesn't wear out so much as dry out. Nearly every slime that goes hard, crumbly or sticky got there through air, heat or hands, and all three are easy to manage once you know what they do. This guide covers how to store slime, homemade or bought, how long it lasts, and how to tell when its time is up.
Does slime dry out?
Yes. Slime made from glue is mostly water held inside a stretchy network, and that water slowly escapes into the air. Leave the lid off and you can feel the change in an afternoon: the surface firms up first, then the stretch goes, then it starts to tear.
Which slimes dry out fastest?
Every slime dries out in the open, but some show it sooner:
- Water, clear and jelly slimes carry the most water, so they dry the fastest. They lose their shine and their flow first.
- Cloud slime loses its drizzle and starts to turn crumbly.
- Butter and clay slimes lose their softness and spread less easily.
- Slimes with foam or beads can start to shed as the slime around them firms up.
The answer to all of them is the same: an airtight tub.
How should I store slime?
- An airtight container, every time. A screw-top tub with a good seal is ideal. A bag or a loose lid lets the air in.
- A container that fits. A slime rattling around in a big tub has more air to lose its water to. Choose one it nearly fills.
- Somewhere cool and out of the sun. Heat softens slime and can turn it runny or sticky. Keep it away from windows, radiators and hot cars.
- Lid on during play. If you set it down for a while, put it back in its tub.
How do I store homemade slime?
The same way, with two additions. Let a fresh batch rest in its sealed tub for a few hours before you judge it, because slime keeps settling after you make it. Then label the tub with the name and the day you made it, so you know which is which and how old each one is.
How long does slime last?
With good storage, a well-made slime can last for months, often longer. How you play with it matters as much as how you store it: clean, dry hands and a clean surface keep dirt and oils out of it.
Why does slime get sticky?
Usually heat, from the room or from your hands, or a lot of play in one go. Let it cool in its sealed tub for a while and it often comes back on its own.
If it stays sticky, it needs a little activator worked back in, a small amount at a time. If you have one of our jars, that's what the care packet that came with it is for: follow the card. Our Slime Care 101 lesson in The Lab walks through bringing back a slime that has gone sticky, or too far the other way.
What if my slime is already dry?
A slime that has only just started to firm up can often be softened with a few drops of warm water, kneaded in slowly. A slime that has gone fully hard, or tears instead of stretching, is a bigger job. That's where the Reactivate and Emergencies chapters of our Slime Care 101 lesson come in.
When is it time to let it go?
- It smells off or sour.
- You can see spots of mold or anything growing on it.
- It has changed color in patches.
- It won't come back however you treat it.
Any one of those, and it's done. It's slime: the next one is a batch away.
Slime on clothes, carpet or hair?
We gave that one a whole lesson of its own in The Lab. Help! My Slime Made A Mess covers hair, carpet and couches, stains that stayed and slime that went through the wash.
The best way to always have fresh slime
Make it. That's what we'd tell anyone. A batch of the simplest slime takes minutes, and once you can make one you never run out. Start with our guide to making slime, which has a starter recipe you can make tonight. If you're wondering whether making your own is worth it, here's how it compares to buying a jar.
Our formulas now live in The Lab: a new slime every Friday, each with its exact ingredients and a step-by-step video of our founder, Jacob, making it, plus lessons on everything from textures to care. Step inside The Lab.