Making slime with sodium tetraborate, commonly known as borax, requires just three ingredients: borax powder, white or clear PVA glue, and water. The process takes about five minutes and produces a stretchy, satisfying slime when the borax solution chemically cross-links with the glue’s polymer chains. Here’s exactly how to do it, what can go wrong, and how to fix it.
What You’ll Need
Your ingredient list is short:
- Sodium tetraborate (borax powder): Sold in the laundry aisle of most grocery stores, typically under the brand name 20 Mule Team Borax.
- PVA glue: White school glue or clear glue both work. Elmer’s is the most reliable option because its PVA concentration reacts consistently with borax. Other PVA-based school glues will also work, but avoid super glue, rubber cement, or epoxy, which won’t react with the activator at all.
- Warm water: Helps the borax dissolve and the glue mix evenly.
White glue produces an opaque, classic slime. Clear glue gives you a translucent, glass-like result. Choose based on the look you want. You’ll also need two containers, a spoon, and a measuring cup.
Step-by-Step Recipe
Start by making your borax activator solution. In one container, measure 1 cup of warm water and stir in 1 teaspoon of borax powder. Keep stirring until the borax has mostly dissolved. A small amount settling at the bottom is fine and won’t cause problems.
In a second container, combine 1/4 cup of warm water with 1/4 cup of PVA glue. Stir until the mixture is smooth and uniform. This is where you’d add food coloring or glitter if you want them.
Now bring the two together. Spoon about 4 teaspoons of the borax solution into the glue mixture, stirring as you go. The slime will begin forming almost immediately. You’ll see it pull away from the sides of the container and clump together. Once it’s too thick to stir, pick it up and knead it with your hands for two to three minutes until it reaches a smooth, stretchy consistency.
Why This Works
PVA glue is a liquid polymer, meaning it’s made of long, flexible molecular chains floating loosely in water. When you add the borax solution, borate ions from the dissolved sodium tetraborate latch onto the chains and form bridges between them. These bridges, called cross-links, connect the loose chains into a three-dimensional network. The borate ions bond to specific spots on the PVA chains through a combination of hydrogen bonds and reversible chemical bonds, creating what chemists call “di-diol” complexes (each borate ion links two separate polymer chain segments together).
This networked structure is what gives slime its unique behavior. It’s neither a true solid nor a true liquid. Pull it slowly and it stretches. Yank it fast and it snaps. Roll it into a ball, set it on a table, and it slowly flattens. This viscoelastic quality comes directly from the cross-linked polymer network the borax creates.
Adjusting Consistency
The ratio of borax solution to glue determines everything about your slime’s texture. Too little activator and you’ll have a sticky, goopy mess that clings to your hands. Too much and the slime turns stiff, rubbery, and tears instead of stretching.
If your slime is too sticky, add the borax solution one teaspoon at a time and knead it in. Give each addition 30 seconds of kneading before deciding if you need more.
If your slime is too stiff or rubbery (over-activated), you have several options. Kneading in a small amount of lotion or vegetable glycerin is the standard fix, as both help soften the cross-linked network. Plain water can also help. Time works too: all borax slime naturally loosens up if you leave it alone for a day or two, since the cross-links are partially reversible. Shaving cream is another option that adds volume and softness simultaneously.
Safety Precautions
Sodium tetraborate is not a harmless household product. In the diluted amounts used for slime it poses low risk, but borax is toxic if swallowed. Clinical reports of boric acid poisoning in children include vomiting, diarrhea, abdominal pain, and in severe cases, seizures. Keep borax powder out of reach of young children, and don’t let kids make slime unsupervised if they’re young enough to put things in their mouths.
Skin irritation is the more common concern. Some people develop contact dermatitis from handling borax slime, especially with prolonged or repeated play. Washing your hands after playing with slime reduces the risk. If you or your child has sensitive skin, wearing thin disposable gloves during play is a simple preventive step. If redness or a rash appears, stop handling the slime and apply a basic moisturizer to the affected area.
Storage and Shelf Life
Homemade borax slime doesn’t have a fixed expiration date, but it will degrade over time. Store it in a sealed plastic bag or airtight container after each use. This keeps it from drying out and limits its exposure to dust and bacteria. Refrigerating the container can slow mold and bacterial growth further.
Most borax slimes stay usable for one to two weeks with good storage habits. If the slime becomes discolored, develops an off smell, or starts falling apart, throw it away. Because slime picks up whatever it touches (pet hair, crumbs, dirt from hands), playing on a clean surface and washing your hands before handling it will extend its life.
White Glue vs. Clear Glue
White PVA glue produces a thicker, more opaque slime that holds its shape well and is more forgiving with borax ratios. It’s the best starting point if you’re making slime for the first time. Clear PVA glue creates a transparent slime that looks impressive but requires a bit more precision. It tends to be stickier during the initial mixing phase and may need slightly more borax solution or a longer kneading time to come together. Clear slime also shows air bubbles, so letting it rest in a sealed container for a day or two after making it will give you that crystal-clear look.
For fluffy slime, use white glue and fold in shaving cream before adding the borax solution. The shaving cream introduces air pockets that make the slime light and puffy while the borax still handles the cross-linking.