Safety
Borax-Free Slime: The Truth About Contact Solution
Most “borax-free” slime recipes still contain boron. What French health authorities say, the gentlest glue recipe and 5 slimes that are truly boron-free.
“Borax-free slime” is one of the most common searches parents make, and for good reason: borax has a bad reputation. But that promise often hides a misunderstanding. Most “borax-free” recipes still contain boron, just in another form. Here’s what you need to know, plus the recipes that are truly boron-free.
Why borax has a bad reputation
Borax (sodium tetraborate) is a powder that, once dissolved in water, turns glue into slime in seconds. It was the activator in the very first slime recipes. The problem: in Europe, borax and boric acid are classified as toxic to reproduction, and in 2018 ANSES, France’s food and health safety agency, reminded parents that children shouldn’t handle them over and over. Since 2012, they haven’t been sold to the general public as pure substances in the European Union. Authorities have also reported skin irritation and burns in children who made slime with laundry detergent or other household products used for the wrong purpose.
The mix-up: “borax-free” doesn’t mean “boron-free”
For PVA glue to turn into slime, you need borate ions: they link the glue’s long chains together. Every activator for glue slime provides them:
- the contact lens solution used in most “borax-free” recipes contains boric acid and sodium borate;
- the bottled activators sold for slime are borate solutions;
- liquid laundry starch, used in many classic recipes, also contains sodium borate.
So a contact solution recipe is “free of borax powder,” not “boron-free.” That’s no reason to panic: the amount is small and diluted in lots of glue. But it is a reason to stick to good habits: an adult pours the activator, everyone washes their hands, and nobody plays with it for hours every day. We compare all the options on our slime activator page.
What about laundry detergent?
Lots of videos, and even some AI-generated search summaries, suggest a “glue + liquid laundry detergent” slime. Some detergents contain borates; others contain only cleaning agents and fragrance. Either way, detergent isn’t made for a child to knead with bare hands: ANSES and the DGCCRF (France’s consumer protection authority) cite cases of severe dermatitis linked to these uses. You won’t find a single detergent recipe on this site.
The gentlest recipe with glue
If you want real, stretchy slime, the most sensible recipe is still the one with contact lens solution and baking soda: ½ cup (120 ml) of glue, ½ cup (120 ml) of water, ½ teaspoon of baking soda and about 1 tablespoon of contact lens solution, added little by little by an adult. Check the label: it should list boric acid and sodium borate. It’s explained step by step in our easy slime recipe, and the Slime Quantity Calculator scales it to fit your bowl.
Truly boron-free recipes
For zero boron, you have to skip the glue. You no longer get a “polymer slime” in the strict sense, but you do get doughs that come very close, made with kitchen ingredients:
| Recipe | Ingredients | Texture | Best for |
|---|---|---|---|
| No-glue slime (oobleck) | Cornstarch and water (2 parts to 1) | Hard when you tap it, runny when it rests | Ages 3 and up, super simple |
| Marshmallow slime | Marshmallows, oil, cornstarch | Stretches and molds | Ages 3 and up, an adult does the heating |
| Chia seed slime | Chia seeds, water, cornstarch | Gooey and full of seeds | Ages 3 and up, make it the night before |
| Fiber slime | Psyllium husk powder and water, heated | Super stretchy | Ages 6 and up, an adult does the heating |
| Gelatin slime | Gelatin, boiling water, corn syrup | Gooey and stringy | Ages 4 and up, an adult handles the boiling water |
These doughs have one thing in common: they don’t keep well (from a few hours to a few days), and they’re not for eating, even though the ingredients come from the pantry. They’re perfect for younger kids and for an afternoon of crafting.
What about homemade doughs?
If what your kids really want is to squish and shape, all of our homemade doughs are boron-free: playdough, cloud dough, moon sand or foam dough.
The bottom line
- “Borax-free” usually means “made with a different, more diluted boron activator.”
- No borax powder, no laundry detergent.
- With glue: contact lens solution and baking soda, poured by an adult.
- For zero boron: cornstarch, marshmallows, chia, psyllium or gelatin.
All the safety rules, including for store-bought slime, are in our parents’ guide.