Thanks everyone
The information about the soldering iron comes from personal experience - it's too easy for concentration (and the hot soldering iron) to slip when tired or building a stack of bin cages. Believe me when I say oooooow! Thank goodness for some lovely nurses at work who dressed the burn for me. I had got a bit blasé about melting plastic but it reminded me to be more careful in future. I can't emphasise enough the importance of working so that the soldering iron is moving away from yourself so any slips won't hit your clothes or skin.