Growing salt crystals
Recommended age: 8+. Adult supervision required! From a saturated table-salt solution we grow sparkling cube-shaped crystals on a thread over several days — a patience game that can start your own mineral collection.
Chemicals
- 100 g table salt (additive-free salt works best — anti-caking agent makes the solution cloudy) — additive-free salt works best — anti-caking agent makes the solution cloudy
- 300 ml water
Procedure
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The hot salt solution can scald: heating and pouring are strictly the adult's job, in oven gloves! You watch and take notes with your goggles on, and never put the finished crystal in your mouth.
Safety! -
The adult heats 300 ml of water in the saucepan until it starts steaming — it does not need to boil.
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The adult stirs the salt into the warm water spoonful by spoonful. You count the spoons! The solution is saturated when, despite stirring, the last spoonful of salt no longer dissolves.
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The adult pours the solution into the jar, leaving the undissolved salt behind in the saucepan.
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Tie the thread to the middle of the skewer and lay the skewer across the jar mouth so the thread hangs into the solution without touching the walls or the bottom.
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Put the jar somewhere calm and warm and drape a paper towel loosely over it to keep dust out. From here on, patience plays the lead role.
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If a salt crust forms on the surface after a day or two, lift it off gently — the water keeps evaporating and the crystals on the thread keep fattening. The longer you wait, the bigger they grow.
Technique -
After about 5 days, lift out the thread and gently blot the crystals dry with a paper towel.
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Examine the crystals with a magnifying glass: they are all built from tiny cubes! Keep a growth diary — draw or photograph how big they got.
Apparatus
- 1× small saucepan
- 1× jar or thick-walled glass — kb. 0,5 l
- 1× cotton thread — kb. 15 cm
- 1× wooden skewer or pencil
- 1× tablespoon
- 1× oven gloves
Frequently asked questions
- Why does it work?
- More salt dissolves in warm water than in cold, and water slowly evaporates from the standing solution. As the solution cools and the water dwindles, the 'excess' salt particles build themselves into an ordered lattice on the thread. The lattice of table salt is cubic — which is why cube-shaped crystals grow.
- Why is nothing growing, or why is my solution cloudy?
- The most common culprit is anti-caking additive — use additive-free salt. The solution may also not have been saturated: have the adult rewarm it and dissolve a few more spoonfuls of salt.
- Does it work with sugar too?
- Yes! Rock candy grows exactly the same way, just more slowly and more stickily — expect one to two weeks. It is worth running both in parallel and comparing the crystal shapes.
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Every version of this image is kept. Nothing here was photographed in a lab — the illustrations are generated on ATAILA hardware, and when the models or the prompt improve we regenerate and keep the old one so the difference is visible.