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.

 

Then 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.

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

You can see how the crystals were cubic:

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

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

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

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!

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: 

2 days later we did the same with the blue:

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

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