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The common table salt is sodium chloride (NaCl) and it can give good satisfactions to the lovers of big and regular crystals. In fact, this salt can form big cubic crystals from its solutions but, to obtain the best results, with big and regular crystals (at least, some cm of side), it's necessary to follow some tips and also to be lucky.

Firstly, remember that NaCl solubility varies little with temperature, as the solubility tables (available in the Internet too) can show:

* 35.7 g/100 ml of solution at 0C
* 38.5 " " at 100C

so, it's very difficult to obtain good results only heating the solution until total dissolution of the salt and, then, let it cool to profit of the decrease of solubility to get the crystals. This would be easier with KCl, for example, with a higher variation of solubility depending on temperature.
Instead, you can only let the solution evaporate at a constant temperature, until precipitation.
Here is a simple procedure:

1) Dissolve 1 Kg of NaCl in 3 Kg or litres of distilled water (to avoid further salt impurities added to the solution). You will obtain a 25% NaCl solution in weight.

2) Filter with a wide sheet of fast filtering paper in a big funnel this solution. This, because the table salt normally produces a turbid solution for the presence of other slightly soluble salts, like calcium carbonates and sulfate and magnesium carbonate, naturally present or added, to enrich its mineral content for diet. Collect the filtered liquid in a very clean and smooth plastic or glass basin, to have at least 10 cm of liquid level.

4) Cover well with a clean smooth paper sheet, fixing it with adhesive tape to the exterior walls of the basin (letting free one side or two to control the crystallization progress) to avoid as much as possible that dust reaches the solution.
In fact, the more are the solid impurities in the solution and the defects of the inner container surface, the more and smaller are the crystals that can find a great number of centres around which to aggregate themselves, while your task is getting them few and big.

5) Store it in a quiet room, garage or cellar, not under the sun and not close to heat sources to avoid excessive temperature variations between night and day and a too fast evaporation. A variable environment, in fact, disturbs the regularity of the crystallization that must be slow, progressive and stable in its conditions.
For the same reason, avoid to move the plastic basin.

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