What Happens When You Microwave Soap: A Sudsy Surprise

Have you ever wondered what would happen if you put soap in the microwave? Perhaps you have heard some rumors or seen some videos online that claim microwaving soap leads to a sudsy surprise, but is it true? In this article, we will explore the science behind microwaving soap and what exactly happens when you do it.

What Happens When You Microwave Soap?

Microwaving soap can result in a chemical reaction called saponification. This occurs because soap is typically made via a chemical reaction between lye and fats or oils. During saponification, the lye and oil/fat molecules are transformed into soap molecules and glycerin.

When you microwave soap, the microwaves cause the soap molecules to vibrate rapidly, which can result in the soap heating up and changing its physical characteristics. Depending on how much water is in the soap and how long it is microwaved, the soap may begin to melt or even bubble and expand.

The Sudsy Surprise

Perhaps the most exciting part of microwaving soap is the sudsy surprise that can occur. As the soap molecules heat up and vibrate, they can become agitated and start to create bubbles. This can result in a sudsy foam that expands out of the soap and fills up the microwave. It is important to note that this foam can be messy and challenging to clean up, so proceed with caution.

Microwaving Different Types of Soap

While many kinds of soap will create a sudsy surprise when microwaved due to the saponification process, some types of soap may behave differently. For example, clear glycerin soap may not create as much foam as opaque soap, while liquid soap may not respond at all.

Is Microwaving Soap Safe?

While microwaving soap can be a fun and interesting experiment, it is essential to do so safely. Be sure to only microwave soap in a microwave-safe container and do not microwave for too long. If the soap begins to expand or the container gets too hot, immediately stop the microwave and let the soap cool down before attempting to remove it.

Additionally, be aware that soap that has been microwaved may no longer be safe to use for cleaning or personal hygiene purposes. The saponification process can alter the structure of the soap, which may affect its effectiveness or safety.

The Benefits of Experimenting With Soap

While microwaving soap can be a fun way to spend an afternoon, it can also be a valuable learning experience. By experimenting with different types of soap and microwaving durations, you can begin to understand more about the properties of soap and how its composition affects its behavior. Additionally, the sudsy surprise that can result from microwaving soap can be fascinating to observe and provide a unique experience that can be enjoyed by both children and adults.


Microwaving soap can result in a sudsy surprise due to the saponification process that occurs when the soap molecules are heated and agitated. While this can be a fun and educational experiment, it is important to do so safely and be cautious of the potential for mess and hot containers. By gaining a greater understanding of soap through experimentation, we can appreciate the chemistry behind this essential household item.

Common Questions and Answers

  • Can I microwave any kind of soap? While most types of soap will create a reaction in the microwave, opaque soap tends to produce the most dramatic results.
  • What happens if I microwave liquid soap? Many liquid soaps will not produce a reaction in the microwave, as they are already in liquid form and do not contain the necessary ingredients for saponification.
  • Is microwaving soap dangerous? Microwaving soap can be safe, as long as it is done in a microwave-safe container and is not microwaved for too long. However, using microwaved soap for cleaning or personal hygiene purposes may not be safe, as the saponification process can alter the soap’s properties.
  • Why does soap create bubbles when microwaved? When heated in the microwave, soap molecules vibrate rapidly and agitate, which can result in the creation of bubbles and foam.


“Microwaving Soap: The Chemistry Behind It.” Compound Interest, 6 Jan. 2015, www.compoundchem.com/2015/01/06/microwavingsoap/.

“Microwaving Soap? | The Sci Guys: Science at Home.” YouTube, The Sci Guys, 4 Oct. 2013, www.youtube.com/watch?v=VwzvRjuJhW8.

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