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02/05/2016

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Messy Science: Non-Newtonian Gloop

02/05/2016

It started with a conversation in the ballet class waiting room.  Quite how or even why we were discussing walking on custard I really have no idea, but the topic came up and with it the mention of YouTube videos showing just what you’d have to do to walk on a liquid.  I knew the theory; if you make a non-Newtonian liquid (which means Birds’ best custard powder custard not the sort you’d actually want to eat) then the impact of your feet hitting the custard renders the liquid a solid and you can skip right over the surface; but sometimes seeing has to be believing, and so really remarkably soon after we got home from ballet, the girls are I were glued to the screen watching this fabulous piece of mad science:

I think after that Kitty was ready to flood our patio with custard and spend all afternoon dancing on it but we don’t have quite the same machinery available for the making of the gloop, our patio isn’t terribly well draining, and her father believed that custard is for eating with jelly and ice cream and not for dancing on (he is right but only if it’s real custard not cornflour and sugar).  But the idea of making gloop for them persisted, especially when I realised that it’s actually been a little while since we made it last, and Pip has never been old enough to have a play.

Space for the Butterflies: Messy Science - Non Newtonian Gloop

Cue one table moved outside onto the patio, and the ingredients assembled:

  • Cornflour (cornstarch)
  • Water
  • Food colouring
  • Three very eager children armed with plastic spoons

Space for the Butterflies: Messy Science - Non Newtonian Gloop

I find that a rough measure of a heaped cup of cornflour to a cup of water produces nicely runny but solid gloop, but it’s always useful to keep a water bottle on hand because it does dry out as you play with it, and you sometimes need to give it a bit of a splash more to get it moving again.  We start with a mound of cornflour straight onto the table, make a well in the centre and then fold the sides in by gently stiring with our fingers.  Spoons and bowls are all very well but because the gloop will resist any strong motion because impact turns it solid, I find it harder to actually stir it than to just splodge it together.

Space for the Butterflies: Messy Science - Non Newtonian Gloop

Gloop is definitely one of life’s simple pleasures.  We started just by pushing it around and picking it up, and Kitty’s old enough now that she can grasp that if she wants a bit to stay solid she has to keep it moving.  There’s just something so weird and wonderful about holding a solid ball that you’ve been rolling between your hands and watching it melt and drip through your fingers.

Space for the Butterflies: Messy Science - Non Newtonian Gloop

We could have kept playing like that for ages but I’d brought home three little tubes of gel food colouring for the trio to have a little fun playing with; because it’s gel rather than a watery liquid it sits on the gloop rather then being immediately absorbed by it which means that you can swirl it into some incredibly gorgeous marble patterns and then move two colours together to make green and an orange that matched the loveliest of blush roses.

Space for the Butterflies: Messy Science - Non Newtonian Gloop

Space for the Butterflies: Messy Science - Non Newtonian Gloop

This was admittedly the point that I realised that really old clothes might have been a better idea – Pip’s shirt and vest are currently having a nice long soak overnight to draw out the food colouring – but it was worth it to see how much they enjoyed just getting stuck in and pushing it about.

Space for the Butterflies: Messy Science - Non Newtonian Gloop

We played together for ages, and then when Pip started to loose interest he and I went to play in the rest of the garden and left the girls too it and they played for ages, right up until it rained! But before then they’d make gloop spirals, run it through each other’s hands and scooped it all up into the cup measure to make what they told me was a gloop swimming pool, presumably for a teeny tiny gloop person.

As you can see from the pictures, gloop is, in our house at least, definitely an outdoor science; all three children went straight in the bath once we’d finished! The rest of the clean up though is pretty simple; the spoons went in the washing up, the cornflour went back in the cupboard and Kitty rinsed the table down with the garden hose – a job I think she enjoyed nearly as much as the gloop.

It’s definitely a science we’ll be bringing out again during the summer and I’m starting to think about ways to tweak it – I wanted to try sprinkling on popping candy but couldn’t find any, and my substitutes (extra strong mints and refreshers) did nothing but provide a slightly strange smell.  Do you think popping candy would react to the water in the liquid, or just sit on the top and look at me? Or is there anything else to do with gloop that I really must try?

Space for the Butterflies - how to make Non-Newtonian Gloop - Messy Science for Kids