Allgemein · Parenting

Volcanic Rock Candle Experiment for Children

I have spoken before on the blog about Number Two, my pre-schooler, and his interest in learning. In recent times that interest has interest has manifested itself in experiements.

We’ve been following Science Wows over on Facebook and have been having a go at the experiements Naomi and her junior scientist have been carrying out. You can find them for yourself here.

Our Accidental Experiment

A couple of weeks ago our toddler, Number Three, did a little experiement of his own. While we were having dinner, he poured his glass of mineral water over the tea light that was burning on the table.

The result was fantastic. The molten wax set because of the cold water landing on it. But the bubbles in the water caused the wax to rise up within the glass tea light holder and set around the bubbles!

Once we poured off the water and removed the wax from the glass, we were able to get a good look at it. The perfectly ordinary tea light now has the appearance of a piece of volcanic rock.


Number Two was amazed by the change in the candle. We decided to try to recreate what had happened and watch the transformation take place. There was just one problem – we had no more sparking water.

Budding scientists that we are, were were not deterred by this. We just had to have a little think about what we could use instead. What did we have in the house that was bubbly like sparkling water?

One solution we came up with was to use cola. Another possibility was to make our own fizz using something we had learned in previous experiments – that combining an acid such as vinegar with a base such as bicarbonate of soda creates carbon dioxide gas. Adding water would, hopefully, give us carbonated water which would, hopefully, give a similar result to the sparkling water.

And so our home grown experiment began.


Here is what we needed:

An empty plastic bottle

A funnel

Some kitchen roll to wipe up any spills

A small amount of tap water

1 tsp bicarbonate of soda

30ml vinegar

A small amount of cola

2 tea lights and sturdy, close fitting containers to hold them in. We used very thick glass tea light holders, as seen in the photo above.

The Experiment

Place the tea lights in their holders. Light the tea lights and leave for 15 to 20 minutes to melt. Do not leave children alone with lit candles!

Place the funnel into the empty plastic bottle, pour approx 50ml tap water in and then add 1 tsp of bread soda (bicarbonate of soda). Swirl the bottle to dissolve the bread soda.

Add the vinegar to the water and bread soda solution. The solution will fizz up inside the bottle.

Immediately pour some of the fizzing solution over one of the tea tights.

Pour a similar amount of cola over the other tea light.

Leave each for a moment or two to set, then pour off the liquid and compare the results.

This is what our three looked like – the original, the homemade fizz and the cola.


Why not have a go of this yourself at home and let us know how you get on.

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