Density of Ice question...

[Cr0nJ0b]

Here is the setup. I just bought a shaved Ice machine from Big lots! ... Well actually, my wife bought it...I thought it looked way too cheap...but anyway...

So in the instructions it tells you to load the ice into the top bid where it spins around and gets shaved into the container below.

In a number of the reviews and in the manual itself it suggests leaving the ice out for 20-30 minutes to let it "soften" up a bit...

That confused me. I thought that ice had the same density or "hardness" regardless of how cold it was.

That's my question. Does Ice get harder or more dense as it gets colder?

Maybe they are saying that the ice should be closer to it's melting point, but I'm not sure how that would help the shaving process...

thanks for the input.

 

[Zorander]

Maybe they are saying that the ice should be closer to it's melting point, but I'm not sure how that would help the shaving process...

I believe this is what the manual is referring to (although it probably will read too hard to consumers if they go into the technical details).

It makes it easier for the dynamo & blade to cut through than if the ice was still rock hard.

 

[John Connor]

Well, I know icebergs have certain densities. http://wiki.answers.com/Q/What_is_the_density_of_an_iceberg

Try shaving an iceberg! LOL!

 

[SecurityTheatre]

My only real world experience with this is hockey.

When it is REALLY cold, the ice dulls blades rapidly. At some temperature, the blades generate more friction on the surface.

Both of these are likely because some component of cutting ice involves melting. When you apply pressure to ice that is near melting, you actually melt thin layers of it. This is, after all, how ice skates work. The pressure of a body on a thin blade temporarily liquefies a thin layer of ice and provides a low-friction buffer for the skate.

When ice is EXTREMELY cold, it behaves more like rock and you have to mechanically scrape it off.

I suspect this is some factor of it.

 

[Gibsons]

I think it gets harder as temperature drops. You're basically looking at hydrogen bond strength and that can vary with temperature (and other things). There are a dozen or so phases of ice though, and that can make things very complicated.

 

[Cr0nJ0b]

Thanks for the great responses.

As a data point I made (well my wife made) snow cones this weekend and allowed the ice to sit out first. I noticed that the ice did cut faster but also it cut into larger chunks relatively. With the really cold ice you get a snow like output and with the warmer ice you get more of the crunchy ice bits in consistency. it's more like highly crushed ice rather than shaved ice.

I didn't know that the hardness of ice changed...and your reference to the increased strength of hydrogen bonds make sense. I sort of thought of this as a density question but density doesn't change...it just gets harder...interesting..

thanks!

 

[MegaVovaN]

Yes it does get more dense with colder temp, check this out:
http://www.engineeringtoolbox.com/ice-thermal-properties-d_576.html

 

[Matt1970]

Just like ice cream gets a lot harder the colder it gets.

 

[MrDudeMan]

Yes it does get more dense with colder temp, check this out:
http://www.engineeringtoolbox.com/ice-thermal-properties-d_576.html

Wait, what? The density in that chart decreases as temperature decreases.

 

[pandemonium]

Wait, what? The density in that chart decreases as temperature decreases.

You're just confusing the 0°C (ice) to 0.01°C density (water) (and this is due to the aeration of water as it ices). From 0 and lower the density of ice gradually increases.

 

[SecurityTheatre]

Wait, what? The density in that chart decreases as temperature decreases.

Nothing in that chart matches what you're saying. Are you sure you noticed the negative numbers in the temperature scale?

 

[MrDudeMan]

You're just confusing the 0°C (ice) to 0.01°C density (water) (and this is due to the aeration of water as it ices). From 0 and lower the density of ice gradually increases.

Nothing in that chart matches what you're saying. Are you sure you noticed the negative numbers in the temperature scale?

Obviously I shouldn't try to think that late at night. I could swear the numbers were decreasing, lol.