Boiling water and food dye?

What could possibly go wrong…

Before the snow arrived in Ottawa, we started experimenting with rainbow ice blocks. My youngest was disappointed that there was no snow for building a fort, or to play in, so we started the process of building up a collection of ice blocks for him to play with.

We started with foil baking tins and empty plastic containers. The foil baking tins didn’t survive round one. His enthusiastic attempts to get the ice out of their molds, resulted in a lot of flattened tins.

Using a large bowl of warm water made it easier to remove the blocks from the plastic containers. If you immerse the outside of the container into the bowl, the hot water will melt the outside of the ice block enough that you can slide it out of the mold.

After seeing my post on Facebook, a friend messaged me to let me know she had experimented with creating ice blocks and had great results with silicone baking molds. Placing them all on baking trays to minimize spillage was another one of her fantastic recommendations!

If your kids want to be involved in the process and you want it to be as safe and mess-free as possible, I would suggest added the food dye to the molds before they arrive to help. They can then fill the molds with cold water.

When our boys were little, we used to fill up ice cube trays with cold water and let them choose the colour of the mini ice blocks. Now that they are older (my youngest is 8 and a 1/2), they are involved in the entire process from start to finish.

Before we start, I make sure they aren’t wearing light coloured clothes and then I ignore their rainbow dyed hands, which usually take a few days to wash off.

When you use cold water, sometimes the food dye doesn’t freeze evenly throughout the block. Cold water also freezes with a more opaque appearance.

Using boiling water means your blocks will freeze faster than they will if you use cold water and the blocks of ice will be crystal clear.

The block on the left was made using boiling water and the block on the right with cold water.

Once our molds are full, we put them on our cement front porch to freeze so we don’t have to worry about finding a flat surface on the lawn to leave them. We tried putting them on our back deck but the dog splashed around in the containers and emptied over half of them.

If you have any mental energy left, this is a great learning activity:

  • Mpemba effect
  • Colour mixing
  • Freezing point and melting point
  • Water safety around hot water

If you just need an activity to pass the time, the rainbow ice blocks are great for decorating forts, having scavenger hunts, building towers, and happy outdoor play time.

Happy backyard magic making!