'Eye of Winter' using a low cost Cold Stage

'Eye of Winter' using a low cost Cold Stage

Yesterday I posted this Triptych of a freezing water droplet, which looked like an eye clouding over. This was done with a very simple low cost cold stage that I assembled for experimenting with macro images. The key element for this is a Thermoelectric Cooler or TEC. Invented by Peltier (look it up on Wiki) these are quite magic things, with fascinating Physics - 'Phonon Drag' - going on inside them. AND they are now very cheap! You can get them on line for about £3 each... but I'd recommend buying a few, as they can be quite easy to destroy.



These are a good size - 40mm square - so you can cool a fair sized object. These are HEAT PUMPS so need a good heat sink - they generate much more heat than the watts you put into them and will quickly fail if you don't mont them on a good heatsink. That said, it doesn't need to be as large as the one on my photo below. This was just one that I recovered from a long obsolete G5 Mac. A slab of Aluminium, copper or Gold (yea right) would work well - but not steel, which isn't a good thermal conductor.



In this set up, the TEC is stuck to the heatsink with a thin layer of epoxy. You can get thermally conductive epoxy, but as long as the layer is thin, it will be fine with normal stuff. The top of the TEC needs a smear of thermal grease on it to give contact to whatever you want to mount on it. I quite like thin mirrors, so you can get a dark background.

These TECs will need about 7 or 8V and 3A to drive them. If you can turn up the voltage slowly you can check if everything works. You will need to check the polarity! Red doesn't mean Positive! It depends which way up you have mounted the TEC. Current one way heats the top, the other way cools it.



Here I've put a drop of water on the mirror and have started to run the cooler. The mirror quickly gathers condensation and freezes over. The drop takes a few minutes to freeze, giving the effect in 'Eye of Winter'.
If you switch off the current, it will quickly warm up and melt, so you can repeat if you don't like the result. You will have a whole kitchen or shed full of materials and liquids you can try freezing. Great for a wet afternoon. You may get interesting colours with a polarising filter above the mirror - it should give a dark background and show up crystals.

I left my set up cooling for an hour or so to see if I could generate some hoar frost... maybe overnight would be interesting!




I hope you have enjoyed reading this. Leave me a message if you need more advice, or if you try this out!