Freezing point of toothpaste

My brother was travelling through Dayton, Ohio last night and he left his luggage in the trunk of his car for several hours. When he got to his hotel room and tried to brush his teeth, he couldn’t as his toothpaste was frozen (or at least couldn’t move by squeezing the tube as hard as he possibly could.)

So, at what temperature does the average toothpaste freeze at? The toothpaste was inside a suitcase, so it should have been insulated somewhat.

The solvent used in toothpaste is a hydroxide liquid commonly known as water. Freezing point: 0 degrees celcius.

Wait a minute. If it’s baking soda toothpaste wouldn’t it freeze lower than that. Seems the soda might act just like salt and keep it plastic just a little lower. Just how does one brush one’s teeth on Everest anyhow ??

“Hope is not a method”

I had assumed that the other materials in toothpaste would have affected the freezing point. However, I can accept 0 celsius.

Well back when I was a young whipper-snapper my mother had us use plain old baking soda when we ran out of regular toothpaste. My cousins after staying over one night distinctly remember it even now and comment on how they now buy baking soda toothpaste for their kids. So if you need a toothpaste that won’t freeze, some baking soda on a brush will do just fine.

Good point. I forgot about it but I used to use “tooth powder” made by Pepsodent and it was packaged in a can and was sold with the toothpaste. I think you can still buy it. I figured it was cheaper than toothpaste.

“Hope is not a method”

Ursa: According to my chemistry teacher anything that dissolves in water will lower its freezing point.

My assumption (probably wrong) was that the powder in toothpaste is no more dissolved in water than, say, dirt is dissolved in water when it makes mud. “Suspended in” sounds closer to the mark. Personal observation has convinced me that mud freezes at the same temp as water. Water is the component that makes toothpaste malleable, the powder technically has a freezing point of several hundred degrees (just below its melting point).

Of course, I’m willing to be convinced otherwise, since I haven’t taken a chemistry class in 20 years.

My Colgate toothpaste lists glycerin as the most abundant ingredient. Glycerin in a 67% solution with water has a freezing point of -47 degrees Celcius, so it is not surprising that your toothpaste did not freeze.


“Believe those who seek the truth.
Doubt those who find it.” --Andre Gide