Yeast is one of the most common catalysts used in elephant toothpaste demonstrations, but it is far from the only option. You can get the same dramatic foam eruption by swapping yeast for potassium iodide, manganese dioxide, or even a slice of raw potato. Each alternative works by doing the same job yeast does: rapidly breaking down hydrogen peroxide into water and oxygen gas, which dish soap then traps into a towering column of foam. The choice of catalyst changes the speed, scale, and practicality of the demonstration in ways worth understanding before you start mixing.
Why People Skip the Yeast
Yeast works in this demonstration because it contains an enzyme called catalase, which speeds up the breakdown of hydrogen peroxide. You dissolve a packet of active dry yeast in warm water, pour it into a bottle of hydrogen peroxide mixed with dish soap, and the catalase goes to work. The result is a satisfying eruption of foam.
The trouble is that yeast can be finicky. It needs warm water to activate, it clumps if you rush the mixing, and the reaction tends to be slower and less dramatic than what you see in viral videos. Those viral clips almost always use potassium iodide or another chemical catalyst, not yeast. If you want a faster, more visually striking result, or if you simply do not have yeast on hand, switching catalysts is straightforward.
The Potassium Iodide Method
Potassium iodide dissolved in water is the catalyst behind most of the giant elephant toothpaste eruptions you see online. When iodide ions meet hydrogen peroxide, they kick off a rapid decomposition. The iodide reacts with hydrogen peroxide to form an intermediate compound, which then quickly breaks apart to release oxygen gas and regenerate the iodide, allowing the cycle to continue.
Research into the mechanism confirms that iodide acts as a true catalyst here. The decomposition proceeds through an intermediate species formed when hydrogen peroxide interacts with iodide. That intermediate rapidly breaks down to release molecular oxygen, and the iodide is recycled back into the solution to catalyze more peroxide molecules.1Journal of the Brazilian Chemical Society. The iodide-catalyzed decomposition of hydrogen peroxide: mechanistic details of an old reaction as revealed by electrospray ionization mass spectrometry monitoring – Section: Results and Discussion This catalytic recycling is why a small amount of potassium iodide can decompose a large volume of peroxide.
To do it yourself, you need three things beyond dish soap and a container: hydrogen peroxide (the higher the concentration, the bigger the result), potassium iodide powder or a saturated potassium iodide solution, and warm water. You mix the hydrogen peroxide with a generous squirt of liquid dish soap and a few drops of food coloring in a tall narrow container. Then you pour in the potassium iodide solution all at once. The reaction is nearly instant. With higher-concentration peroxide, the foam can shoot several feet into the air.
Potassium iodide is sold as a dietary supplement in many pharmacies and health food stores, and it can also be ordered as a laboratory reagent. A saturated solution, made by dissolving as much potassium iodide as the water will hold, gives the fastest reaction. If you use a dilute solution, the foam still forms but rises more slowly, which can be useful if you want a gentler demonstration for younger kids.
Manganese Dioxide as a Catalyst
Manganese dioxide is another powerful catalyst for hydrogen peroxide decomposition. It is a dark brown or black powder that you can find in some pottery supply stores or order from chemical suppliers. Unlike potassium iodide, which dissolves in the liquid, manganese dioxide is a solid that sits at the bottom of the container and catalyzes the reaction at its surface.
Studies of how manganese dioxide interacts with hydrogen peroxide confirm that the oxide surface drives the dissociation of peroxide molecules into water and oxygen.2PubMed Central. Thermocatalytic Behavior of Manganese (IV) Oxide as Nanoporous Material on the Dissociation of a Gas Mixture Containing Hydrogen Peroxide – Section: Abstract Because the reaction happens at the surface, the finer the powder, the faster the decomposition. A coarse chunk of manganese dioxide will produce a slow, steady stream of bubbles. A fine powder will produce something closer to the explosive foam eruption you are after.
The practical advantage of manganese dioxide is that it is not consumed. After the foam settles, you can rinse the powder, dry it, and reuse it. The disadvantage is that it is messier to work with than a liquid solution and harder to find on short notice. For a classroom or science-fair setting where you plan to repeat the demonstration multiple times, it is a cost-effective choice.
Everyday Household Alternatives
If you do not want to buy any special chemicals, a few items from the kitchen can serve as crude catalysts. Raw potato, raw liver, and even a splash of blood all contain catalase, the same enzyme found in yeast. Cut a raw potato into small cubes or mash it, mix it into your peroxide-and-soap solution, and you will get a foaming reaction. Liver works even better because it has a higher concentration of catalase per gram.
The catch is that these biological sources produce a much less dramatic result than potassium iodide or manganese dioxide. The foam rises slowly and tops out at a modest height. If you are working with standard 3% drugstore hydrogen peroxide, expect a gentle overflow rather than an eruption. For a kitchen-table experiment with young children, that is actually a feature: the reaction is slow enough to watch and safe enough to touch.
A few other household items sometimes suggested include lemon juice, baking soda, and vinegar. These do not actually catalyze hydrogen peroxide decomposition in any meaningful way. Baking soda and vinegar produce carbon dioxide gas on their own, which can create foam when soap is present, but that is a completely different reaction. If you want the real elephant toothpaste effect, where oxygen gas from peroxide decomposition drives the foam, stick with an actual catalyst.
Choosing the Right Hydrogen Peroxide Concentration
The concentration of hydrogen peroxide you use is arguably more important than the catalyst you pick. The standard brown bottle at the drugstore is 3% hydrogen peroxide. It works, but the results are modest. For a visibly impressive eruption, most demonstration guides recommend at least 6% to 12% peroxide, and the truly dramatic versions use 30% or higher.
Higher-concentration peroxide means more oxygen is released per milliliter of liquid, which means more foam, faster. Research on the elephant toothpaste reaction has shown that temperature also plays a role: performing the reaction at room temperature produces a reaction roughly three times faster than performing it on ice, underscoring how sensitive the decomposition rate is to conditions.3ACS Publications. Elephant’s Toothpaste Used as a Qualitative Demonstration of Rate versus Temperature So if you are using a weaker peroxide, keeping it at room temperature or slightly warmer helps squeeze more performance out of it.
Where to find higher concentrations depends on where you live. Many beauty supply stores sell 6% to 12% hydrogen peroxide as a hair developer. Concentrations of 30% to 35%, often labeled “food grade” hydrogen peroxide, can be found at some health food stores or ordered online. Anything above 12% requires careful handling, which brings us to the safety question.
Safety at Different Concentrations
At 3%, hydrogen peroxide is the mild antiseptic most people know. You can get it on your skin without much concern beyond a brief whitening that fades in minutes. As the concentration rises, the risk changes dramatically.
Research on hydrogen peroxide and skin has shown that low concentrations cause only temporary symptoms like blanching and minor blistering, but exposure to concentrations between roughly 9% and 45% can cause much more serious damage, including destruction of the outer skin layers, redness, and fluid-filled blisters.4PubMed. Hydrogen peroxide and cutaneous biology: Translational applications, benefits, and risks A case report of a worker accidentally splashed with 35% hydrogen peroxide documented severe skin injury with deep tissue involvement, including oxygen bubbles forming beneath the skin and even subcutaneous emphysema detected on a chest X-ray.5Dermatology. Occupational Skin Injury by Hydrogen Peroxide
The practical takeaway: if you are using 3% peroxide, gloves and goggles are a nice precaution but not strictly critical. If you are using anything above 10%, wear chemical-resistant gloves and splash-proof safety goggles without exception. At 30% or higher, treat the peroxide the way you would treat a strong acid. Keep it away from skin and eyes, work in a well-ventilated area, and have running water nearby. Children should not handle concentrated peroxide at all. An adult can prepare the solution and let kids add the catalyst from a safe distance.
The foam itself is generally safe to touch once the reaction is complete, though it may feel warm. The decomposition of hydrogen peroxide is exothermic, meaning it releases heat. With concentrated peroxide, the foam can come out steaming hot. Give it a minute to cool before letting anyone stick their hands in it.
Getting the Foam Taller and Thicker
The dish soap you use matters more than most people realize. The soap’s job is to trap the released oxygen gas inside bubbles. A thin, watery soap creates fragile bubbles that pop quickly, producing a brief splutter rather than a lasting column. A thick, viscous liquid dish soap or even a dedicated foaming agent creates sturdier bubbles that stack on top of each other and hold their shape.
A few tips that make a noticeable difference:
- Container shape: Use a tall, narrow bottle or graduated cylinder rather than a wide bowl. The narrow opening forces the foam upward instead of outward, making the eruption look more dramatic even with the same amount of foam.
- Soap quantity: More is better, up to a point. A tablespoon or two of dish soap per cup of hydrogen peroxide is a good starting ratio. Too little and the oxygen escapes as gas without forming foam. Too much and the mixture becomes so thick that the catalyst cannot mix in easily.
- Food coloring: Drizzle stripes of food coloring down the inside walls of the container rather than mixing it into the peroxide. As the foam rises past the stripes, it picks up the color in streaks, creating the classic elephant toothpaste swirl pattern.
- Warm peroxide: Gently warming the hydrogen peroxide to around body temperature before adding the catalyst speeds up the reaction and produces a more vigorous eruption. Do not heat it on a stove. Setting the bottle in a bowl of warm tap water for a few minutes is enough.
The catalyst delivery also matters. Dumping potassium iodide solution in all at once produces one fast surge. Pouring it in slowly creates a sustained ooze that lasts longer but never reaches the same peak height. For maximum drama, commit to the single pour.
Iron and Copper Catalysts
Beyond the usual potassium iodide and manganese dioxide options, dissolved iron and copper salts can also catalyze hydrogen peroxide decomposition. This is the basis of what chemists call Fenton chemistry, in which iron or copper ions react with hydrogen peroxide to generate reactive oxygen species. The classic Fenton reaction uses iron in an acidic solution to break down peroxide, and copper-based systems follow a similar pattern, cycling between oxidation states as they react with peroxide molecules.6PubMed Central. Performance of Copper as a Catalyst for Fenton-like Processes in Highly Saline Solutions
In practice, neither iron nor copper salts are commonly used for elephant toothpaste because they tend to produce a slower, less visually dramatic decomposition compared to potassium iodide. They are also more likely to produce colored foam (rust-colored from iron, greenish from copper) and can stain surfaces. But if you happen to have ferrous sulfate from a garden supply store, dissolving a spoonful in water and adding it to your peroxide-and-soap mixture will produce foam. The result sits somewhere between the sluggish reaction of a raw potato and the explosive surge of potassium iodide.
Setting Up for Easy Cleanup
Elephant toothpaste produces a surprising volume of foam. A few hundred milliliters of concentrated peroxide can generate several liters of foam within seconds. Planning for the mess is just as important as planning the chemistry.
Do the experiment outdoors or in a bathtub. If you are working on a table, place the container inside a large baking sheet or plastic storage bin to catch overflow. The foam is mostly soapy water with dissolved oxygen, so it rinses away easily, but food coloring can stain porous surfaces like wood or unfinished concrete. Lay down a plastic sheet or garbage bags if you are working on anything you care about.
The leftover liquid at the bottom of the container, once the foam has collapsed, is dilute soapy water. If you used potassium iodide, it also contains iodide ions, which are harmless at these quantities and can go down the drain. If you used manganese dioxide, scoop the powder out before rinsing. It is not water-soluble and can clog drains.
Why the Foam Is Warm
If you have ever touched elephant toothpaste foam right after it forms, you may have noticed it is warm or even hot. The decomposition of hydrogen peroxide into water and oxygen releases energy. With 3% peroxide, the heat is barely noticeable. With 30% peroxide, the foam can come out steaming, and the container itself can become too hot to hold.
This heat release is worth knowing about for two reasons. First, it is a safety factor with concentrated peroxide: the foam and the liquid beneath it can cause mild burns on contact immediately after the reaction. Second, it is actually a useful teaching moment. The demonstration shows in a visceral, tangible way that breaking chemical bonds can release energy. If you are running this as an educational activity, having participants feel the warmth of the container (from a safe distance, after it has cooled slightly) makes the concept of an exothermic reaction click in a way that a textbook explanation cannot.
Temperature also works in the other direction. Starting with warm peroxide speeds things up, and starting with cold peroxide slows them down. Research comparing the reaction at ice temperature versus room temperature found that the room-temperature version ran roughly three times faster.3ACS Publications. Elephant’s Toothpaste Used as a Qualitative Demonstration of Rate versus Temperature Running the experiment at both temperatures side by side makes for a compelling comparison if you want to show how temperature affects reaction speed.
Hydrogen Peroxide Decomposition Beyond the Demonstration
The same basic reaction behind elephant toothpaste shows up in contexts far removed from science fairs. The catalytic breakdown of hydrogen peroxide into water and oxygen is used industrially in applications ranging from wastewater treatment to the manufacturing of lightweight building materials. Researchers have used hydrogen peroxide as a foaming agent in magnesium phosphate cement, for example, producing foam concrete with tunable density and thermal properties by controlling how much peroxide is added and how fast it decomposes.7Elsevier – Construction and Building Materials. Preparation and properties of magnesium phosphate cement foam concrete with H2O2 as foaming agent The principle is identical: peroxide breaks down, oxygen is released, and a matrix (cement instead of soap) traps the gas to create a porous structure.
In biological systems, the enzyme catalase exists precisely because hydrogen peroxide is a toxic byproduct of normal metabolism. Your own cells produce catalase to neutralize peroxide before it damages DNA and proteins. When you mash a piece of raw potato or liver and drop it into hydrogen peroxide, you are watching the same detoxification process that keeps your cells healthy, just scaled up and made visible with soap bubbles. That is arguably the most interesting thing about the whole demonstration: the chemistry behind a party trick is also the chemistry that keeps you alive.