Now summer seems to finally be here, we thought we’d get the sand table out and start playing. We tried to make sandcastles with the dry sand, which didn’t work at all. They just collapsed.
Can you think why this is? What could you add to make the sand more ‘sticky’?
We added a little bit of water, which made the sandcastles a little better, but still not great.
We kept adding water until we could make an almost perfect sandcastle. It took several attempts to get the right combination of sand and water.
The Science bit
You should have noticed that wet sand is much stickier than dry sand. This is because the water forms tiny bridges between the grains of sand which holds them together. This is due to the surface tension of the water. If too much water is added, water fills the space between the grains of sand and the bridges break down.