If you paint watercolours with vodka instead of water, the paint won't freeze on the brush.
Found that handy little tip here:
http://gurneyjourney.blogspot.com.au/2014/03/painting-iceboats.html?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed:+blogspot/NVaYV+(Gurney+Journey)
At James Gurney's blog. If you are unaware of Gurney, he is the genius behind Dinotopia. If you don't know what Dinotopia is, you should Google it immediately.
There's dinosaurs.