Why people put a wooden spoon across a boiling pot; the science behind the kitchen hack

A pot bubbling away on the stove can go from perfectly fine to overflowing in just a few seconds. That's why many home cooks place a wooden spoon across the top of the pot, hoping it will stop the mess before it starts. But does this popular kitchen trick actually work? According to The Conversation, it does (but only for a short time). The reason comes down to the science of bubbles, starch and heat.

Wooden spoon hack

A rapidly boiling pot of plain water usually won't spill over on its own. The real reason for the mess is what gets added to the water. Foods such as pasta, rice, porridge and milk contain carbohydrates or proteins that change the way bubbles form as they cook.

According to The Conversation, starches from foods like wheat, rice, corn and potatoes, along with the milk protein casein, create sticky bubbles instead of ordinary steam bubbles. As the liquid continues to boil, these bubbles stack on top of one another and quickly climb towards the rim of the pot.


With pasta or porridge, the starch forms a gel that coats the bubbles, making them stronger and slower to burst. Milk behaves slightly differently because heated casein creates a foam, but it can rise just as quickly and spill over the edge.

Why do some pots boil over?

The science behind the wooden spoon trick lies in the material itself. Wood is naturally porous when it's dry. Placing a dry wooden spoon across the top of a boiling pot interrupts the bubbles as they reach the surface. The spoon briefly lowers the surface temperature where the bubbles touch it, while its porous surface allows trapped air to escape. This causes many of the bubbles to burst before they can spill over the side. However, this effect doesn't last forever.

How does the wooden spoon trick work?

As the spoon sits over the steam, it absorbs heat and moisture. Eventually, it becomes almost as hot as the boiling liquid beneath it. Once that happens, it can no longer cool the bubbles or burst them as effectively.

That's why some people believe the trick works perfectly while others say it doesn't work at all. In reality, both experiences are correct. The wooden spoon is only effective during the early stages before it becomes saturated with heat and moisture.

What's the best way to stop a pot from overflowing?

The Conversation explains that there are more reliable ways to keep a pot from boiling over. Stirring the food helps break up bubbles, while using the wooden spoon to gently fan the surface can have a similar effect.

Choosing a larger pot also gives the bubbles more room to expand, reducing the chance of overflow. Turning down the heat once the water reaches a steady boil is another simple way to prevent bubbling from getting out of control.

If you need to step away, lowering the heat, switching off the burner or removing the pot from the stove is a safer option than relying on the wooden spoon alone.

The wooden spoon trick isn't a myth, but it isn't foolproof either. As The Conversation explains, it works because a dry wooden spoon can briefly interrupt the hot, sticky bubbles created by starches and proteins. Once the spoon heats up, though, its effectiveness fades, making careful cooking the best way to avoid a messy stovetop.

FAQs

Does a wooden spoon really stop a pot from boiling over?
Yes, but only until the spoon becomes hot and wet.

Which foods are most likely to boil over?
Pasta, rice, porridge and milk are among the biggest culprits.