4: Crystal Growing

eye protection
disposable gloves for handling crystals

What you do

1. 
   To make small crystals of different varieties you need to warm 100cm³ of water and add the amounts of solute below. Stir until no more crystals will dissolve.
   sodium chloride 33g in 100cm³ water
   copper sulphate 30g in 100cm³ water
   sodium sulphate 20g in 100cm³ water
   potassium aluminium sulphate (alum) 39g in 100cm³ water
2. Pour this saturated solution into a large evaporating basin and leave for several days to crystallise.

1. 
   Make a new saturated solution of copper sulphate and allow it to cool down.
2. Place the dish or beaker of new saturated solution in a place where the temperature will vary as little as possible.
3. Using forceps, pick out the best copper sulphate crystal from the evaporating basin.
4. Drop this into the cold saturated solution and leave it for a few days.
5. Using forceps, turn the crystal every day so that it can grow equally on all sides.
   The secret is to keep the solution in a place which is no warmer by day than by night.
6. An alternative method of growing your crystals is to tie a piece of thread around the starting crystal, then suspend it in the cold saturated solution. Leave in a constant temperature environment. (Alum crystals also grow well using this method).
   Use forceps or gloves to handle the crystals.
7. You can grow crystals around a wire shape which can be suspended in the saturated solution. Crystals form best on rough surfaces, so use cotton-covered electrical wire or plain wire wrapped with thread or light string.

1. Dissolve 500g of potassium hexacyanoferrate(III) in 1dm³ of water. Allow this to cool to a manageable temperature and filter the solution while it is still slightly hot.
2. Stand the object you want to coat in crystals in a beaker and pour the filtered solution into this so that it covers the object.
3. Leave to cool. Crystals should start to form after a few hours.