Tuesday, 3 March 2009

Salt Crystals

Littletree has been doing a science experiment - Crystal growing. We decided to start with plain salt crystals; we'll work up to all different kinds eventually.

The project began with a bag of cheap iodised cooking salt, we poured about a cupful into a bowl and poured in boiling water, stirring all the time till the salt was just dissolved.

01 pouring salt02 adding water 

03 stirringThen we poured the solution into three containers and added a few drops of food colouring to each. The blue bowl we did nothing, the red we added a thin strip of fabric dangled into the liquid, and the green we added a single chunk of rock salt as a seed.

04 coloured solutions

There wasn't much change for a few days, but on the morning of day 5, some crystals started forming in the green bowl:

05 day 5 crystals forming

You can see how the crystals were cubic:

07 day5 green

Day 6 we had more green crystals, and the start of some blue ones: 

08 day 609 day6 blue

11 day6 gren

In the evening I gave a bit of a tap to the red bowl, and lo! Day 7 greeted us with red crystals! 

12 day 7

14 day7 red

Day 14; A big chunk of salt was forming up the strip of material in the red bowl:16 day14 red15 day 14

The green one (in the shallowest dish) was almost dry, but since we live in such a humid climate, it never fully dried out - the salt was sucking moisture out of the air some days the salt would be wetter than the day before!

18 day14 green

We decided after a week of it being mostly dry that it was as good as it was going to get in our climate, and we tipped it onto paper towel to soak up the last of the moisture. Completed crystals, day 21: 19 day 21 green crystals

2 days later we did the same with the blue:

22 day 23 blue crystals

The red one took a long time to fully dry out, but here's the finished product, 5 weeks after starting:

CIMG5845Littletree is really happy with her little crystal collection anyway :)


  1. What a neat little experiment! I'm gonna have to try that with my little one.
    You have such a nice blog!

  2. Brilliant! We must start doing experiments and this is a great place to start! Thanks!

  3. Fabulous! Little Z just asked me if we could do the very same thing recently (but with sugar). I'll let you know how it turns out!

  4. What a wonderful experiment! We will have to give this one a go too. We have been a little slack in the experiment dept lately but the boys really love it. Mind you being boys they tend to prefer to blow things up.

  5. That's awesome! What a fantastic thing to do. I remember doing a little bit of that, but my crystals were never quite so cool. :-)


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