Why Do Glasses Stick to Coasters?

By understanding the science behind why glasses stick to coasters, you can make sure your glasses always stay where you want them. So, why do glasses stick to coasters?

The Science of Glasses and Coasters

We all know the feeling: you're enjoying a cold beverage on a hot day, and you set your glass down on a coaster. A few moments later, you try to pick the glass back up, but it's stuck to the coaster!

Why does this happen? It turns out, there's a scientific reason behind this phenomenon. When you set your glass down on a coaster, the heat from the glass transfers to the coaster.

This causes the coaster to expand slightly. At the same time, the moisture from your glass condenses on the coaster, creating a small amount of suction. Together, these two forces cause your glass to stick to the coaster.

the glass of water and drink coasters

The Physics of Coasters

When you place your glass on a coaster, the coaster's surface creates a small amount of friction. This friction is created by the coaster's material sticking to the glass. The amount of friction is determined by the coaster's material and the weight of the glass. The heavier the glass, the more friction is created. This friction is what prevents your glass from sliding off the coaster. So, the next time you're wondering why your glass is sticking to the coaster, remember it's all thanks to physics!

The Chemistry of Coasters

When you set a glass down on a coaster, the friction between the glass and the coaster creates an electrical charge. This charge causes the glass and the coaster to attract each other and makes it difficult to pick the glass up again. But why does static electricity happen in the first place? To understand that, we need to look at the atoms that make up the glass and the coaster.

The Coefficient of Friction

The coefficient of friction is a measure of how much two surfaces resist sliding against each other. When you set a glass down on a coaster, the coaster's coefficient of friction is greater than the glass's coefficient of friction. This means that the coaster will resist sliding on the glass more than the glass will resist sliding on the coaster. This resistance to sliding creates a force that causes the glass to stick to the coaster


When you set your glass down on a coaster, you might notice that it sticks to the coaster. This is because of adhesion. Adhesion is the force that causes two surfaces to stick together. In this case, the glass is sticking to the coaster because the coaster is made of a material that has a lot of friction. Friction is the force that opposes the motion of two surfaces that are rubbing against each other. The more friction material has, the more likely it is to cause things to stick to it.


Condensation is the process of water vapor turning into liquid water. When the temperature of the air around the glass is colder than the glass, the water vapor in the air will condense on the glass. This can happen quickly if the glass is cold and the air is warm, or if there is a lot of humidity in the air. The water vapor condenses on the glass because it is attracted to the colder temperature. The glass will stick to the coaster because the condensation forms a water droplet between the glass and the coaster.

Final Thoughts

Well, does it matter when your glass sticks to the coaster? Definitely, it does. The forces at work here are classic examples of adhesive forces and cohesive forces. Adhesive forces are the attractive forces between two materials that are in contact with each other. In this case, the adhesive force is between the coaster and the glass. Cohesive forces are the attractive forces between particles of the same material. In this case, the cohesive force is between the molecules of the coaster material.

Commonly Asked Questions

Does condensation play an important role when a glass sticks to a coaster?

Yes, condensation plays an important role in a glass sticking to a coaster. When water condenses on the surface of the glass, it creates a thin layer of water between the glass and the coaster.

This thin layer of water acts as a lubricant, allowing the glass to slide on the coaster. Now you know the reason for the sticking.

How do you stop coasters from sticking to mugs and glasses?

There are a few ways to stop coasters from sticking to mugs and glasses.

a mug and the drink coaster
  • One way is to use a coaster with a non-stick surface.
  • Another way is to use a coaster with a weighted bottom so that it stays in place.
  • Finally, you can use a coaster with a suction cup bottom to keep it from sliding around.

How to keep glasses from sticking to coasters?

The simplest way to prevent your glasses from sticking to coasters is to avoid using coasters made of absorbent materials like cardboard or paper.

Instead, use coasters made of non-absorbent materials like glass, metal, or stone. You can also try to avoid using coasters with textured surfaces, as these can also cause your glasses to stick. Finally, make sure to clean your coasters regularly to remove any dirt or debris that could be causing your glasses to stick.

How to make cork coasters not stick to glass bottoms?

There are a few things you can do to make sure your cork coasters don't stick to the bottom of your glass.

  • First, make sure the cork is clean and dry before use.
  • Second, avoid using cork coasters with any type of adhesive on the bottom.
  • Third, try using coasters made of another material, such as silicone or plastic.

How to use table coasters?

Table coasters are used to protect surfaces from water damage. To use a table coaster with a glass of water, simply place the coaster under the glass.

Author - Nurlana Alasgarli
Nurlana Alasgarli           

Content Specialist

Nurlana Alasgarli is a professional copywriter with more than 6 years of creative writing experience. Having lived and experienced all over the world, there are many writing genres that Nurlana follows, including nature, arts and crafts and the outdoors. Nurlana brings life to content creation, captivating her readers.


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