Clear Ice

[KobusDJ]

To make clear ice (those nice looking see through cubes) you need to do the following:

Use clean/pure water (distilled)
Boil it to get rid of the dissolved air
Freeze in layers

Question: Does it mean that the more "milky" your cubes are, the more impure/polluted/contaminated water you have.

[Soutter]

Originally Posted by KobusDJ

Question: Does it mean that the more "milky" your cubes are, the more impure/polluted/contaminated water you have.

Not necessarily ... also has to do with the way it was frozen, if it has melted and refrozen etc.

freezing water slowly will result in clearer ice than water frozen quickly.

also, the older type of ice makers (the ones that spray a steady stream of water into an inverted "cup") make clearer ice than the ones which immerse a cold rod into water.

[MikeAG]

No, it means there is more oxygen dissolved into the water. Your process is simply about removing bubbles of gas. Compressed snow, squished such that there is no place left for the bubbles of air, is clear when it freezes into ice.

Mike

[KobusDJ]

So it is more the trapped oxygen than the impurities.

Those people doing the ice sculptures always amaze me with their "clear" ice.

[TiaanS]

I know that for the construction of the ICE hotel in Kiruna they only use crystal clear ice from the Torne River. The river’s ice got some unique properties in the way that it freezes up as well as the water quality.

[Randy]

Is the "whiteness" not caused by suspended solids in the water?

Mike - you in the UK will not have this YOURS will have only oxygen.

Maybe OT, but most water filters / purifiers (even some that cost R5 - 7k) are ONLY for aesthetic purposes. Removes smell, taste and looks clean.

Dis some research for a guy at Pecanwood a few years ago, he ended up installing a R300k 3x4m room full of purification plant to get rid of all the nasties (microsistoxins etc.) in the "borehole" water. If people REALLY knew what was in that dams water they would not go near it never mind in IT!!!!

No i did not make a fortune, i was only paid for my advise, plant came from USA. They make systems that can remove the 2700 most common chemicals etc from water.

There is a SCARY subject for YOU.

I believe that those impurities ( the natural ones other than the obvious harmful viruses ) contains some nutrients and it keeps your immune system exercised.

I have been drinking from the tap for 25 years and I can't really remember the last time I was horribly sick.

On the subject of clear ice - It is the oxygen that escapes and gets trapped when the water freezes and creates pressure. If you want clear ice try this : boil water and pour it in the ice tray. Try to be gentle when pouring to keep it from dissolving extra air again. Put it directly into a very cold freezer.

[Frans Reichert]

Perhaps I can help.

For background, we manufactor Ice, about 12 ton of it each day, and then we distribute them in Kimberley and serounds. So believe me when I say: I am cool!!

Doesn't matter how clear your ice is, after a time it wil go white, but if jou dip it in water for a moment it wil become clear again.
The icemachines work on a principle that the water keep on moving and freeze on the evaporator. If the water doesn't move you get ice with more cracks and bubbles in.

[ArrieMeyer]

The whiteness is caused by dissolved elements in the water, so using distilled water with the air boiled out will definitely result in clearer ice cubes. Remember: even clean water has some dissolved elements such as oxygen, nitrogen, chlorine, magnesium etc.

It works like this: the higher the temperature of the water, the more dissolved ions can be present in the water. When we make ice cubes, the water cools and solidifies from the outside. The colder water cannot hold as much frozen ions, and therefore the dissolved elements are continiously rejected from the solidification front into the unfrozen water. As the solidification front moves towards the centre, the unfrozen water therefore becomes more and more enriched in dissolved matter, i.e. the concentration of dissolved ions becomes larger and larger. In the end, there is no unfrozen water left, and the dissolved ions simply freeze in. The "white" center is therefore a supersaturated solution of various elements in water, and the clear part is relatively low in dissolved matter, except for the very little that can be in solution at such low temperatures.

Depending on the amount of dissolve matter that we start with, the "white" part may be smaller or larger, sometomes even resulting in a totally "white" ice cube. These sometimes result in Coke (or any other gas cold drink) "boiling" vigorously when the ice is added, as some of the dissolved ions replace the CO2 dissolved in the Coke, whereuopon the CO2 leaves the Coke and make bubbles.

[RedLineR]

Don't worry about milky ice. It's just air.
Water is kinda weird that way, but this is what happens.
As water is cooled, it shrinks. this means that it's density increases.
Right down to around 4°C.
When water continues cooling to below 4°C it starts expanding again. In other words it's density decreases. It still weighs the same, but the volume is occupies becomes larger. You see this in your ice trays in that they look fuller than they did when you filled them with water.
Then as the water solidifies (freezes), it continues to change density. That's when the air in the water can now longer be suspended in the water. so it separates out of the water, but is trapped in the cube.
Nothing to worry about.

Air and moisture works much the same way. As air cools it cannot keep the water vapour in suspension anymore, and the water drops from suspension. We see it as water forming on a cold glass. The glass cools a thin layer of air around the glass to such an extent that the water vapour drops out of suspension and forms droplets on the glass.
Same with rain, which is why we don't often get rain when it's lekka hot. There are ofcourse times that a cold air stream at high altitude meets a nice big cloud and cools it, causing the water vapour to be dropped from suspension. But we mostly get rain in the afternoon when the temps are going down. Water vapour has built up nicely to max capacity at that temperature, and as soon as the temp drops, the water drops out of suspension because the air cannot sustain the amount of water vapour at the decreased temp.

I'm over-simplifying a bit so we don't have to go down to atomic and sub-atomic level, but you get the idea

[DavidW]

Very interesting Frans, one learns new things every day!