Australia's Science Forum

One of my teachers had a wonderful time making honeycomb pumice last period yesterday. Eight groups with hotplates. Apparently the kids loved it - massive boiling over of 'lava' which caught fire and splattered all over the benches and floor. And set off the smoke detectors.
When I went to check it out this morning I found four of the hotplates covered in a black sticky mess. The stuff on the actual element is almost carbonised.
But how do I clean them up?? We've only got ten hotplates in the school, and teachers have ordered them for today.

maybe oven cleaner would work

I think oven cleaner would be the only solution on the metal of the hotplates. If the burnt sugar is in a beaker, I soak them in NaOH solution and they come clean but you could hardly do that to the hotplates. I have often used stainless steel scourers to clean hotplates, but never 10 of them!

"If the burnt sugar is in a beaker, I soak them in NaOH solution and they come clean"
you do not have to soak them in NaOH. Just add water and heat, sugar will dissolve in water

I thought a pasty solution of bicarb on the hot plate quite thick and wet and heat gently while scrubbing might work.
I would be getting the teacher and the kids to do the hard work. Unfortunate that you need them in a hurry.

Jazz wrote:"If the burnt sugar is in a beaker, I soak them in NaOH solution and they come clean"
you do not have to soak them in NaOH. Just add water and heat, sugar will dissolve in water

That will remove the unburned sugar. Unfortunately burned sugar is char. Carbon does not disolve well. The black lumps hold together tightly and have to be scoured off; although soaking will help loosen the char (which may possibly be bound together with some merely caramelised sugar (brown)).