Message 32590 of 39188 in General Discussion

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Here is the Alconomics method

The double freezing of ice is a useful technique in creating super dense, 
super clear ice.  Why double freeze?  From a single freezing, ice will go to 
the temperature of the freezer.  The gas (oxygen, nitrogen, etc…) that has 
been absorbed into an aqueous form will collect into small ‘bubblets’ that 
will further join with other ‘bubblets’ to form bubbles into the semi-frozen 
ice mass.  If this is left to melt, the bubbles of (now un-dissolved) gas will 
escape from the water so on re-freezing the ice will be denser and clearer 
without the ‘mist’ of fine bubbles within the ice.  A third and fourth 
re-freezing of the ice will only clarify the ice further and make even harder, 
clearer ice.  

The freezing of the slabs of ice is best done if plastic containers due to 
their flexibility (helpful while trying to take the slab of ice out of the 
container) and cost.  Ice will also stick to metal easier than to plastic due 
to its thermo-elastic properties.  Depending on the mineral qualities of the 
water you are using to freeze into slabs, the containers will need regular 
cleaning to remove any limescale/mineral deposits that, if left uncleaned, can 
contaminate the ice with flakes of white mineral deposits.  

From a service point of view, the in-bar freezing of ice can allow for several 
different types of ice to be made (e.g. Ice from Evian, from Ty Nant and from 
Highland Spring) to cater for even the most discerning customers.  The water 
used can be chosen for its softness, its ‘bite’ or any other characteristics 
required by the bar/customers.


hope its useful... it is tried and tested...

aw


> Somewhat in relation to this demonstration, but also just in 
> general...
> 
> Does anyone know what it takes to get solid, clear, ice in large 
> lumps from a domestic freezer?
> I've tried a few times over the last week to see if there was a 
> secret I was missing. I'm freezing tap water in 1 litre yogurt 
> containers. Slightly tapered so i guess it has room to expand if 
> needed, but it keeps coming out mostly opaque or cracked.
> 
> In the interests of experimentation I've been trying additives to see 
> if there's a household ingredient that'll make a difference. A tsp of 
> sugar, a tsp or vinegar didn't work. I know salt'll make it cloudy.
> 
> Is there some chemistry school trick anyone knows? Is it better to 
> freeze slow or fast? Stir it in the middle? 
> 
> .dan.
> 
> [edit]
> Heh, I should have started with Google.
> http://www.edgerton.org/resources/kidscorner/kidscorner/clearice.html
> 
> Apparently distilled water + boiling + mild agitation and slow 
> bottom-up freezing are all good factors.