Pipe Lagging Microbore Pipes

Closed cell continuous lengths are used for aircon pipework which is often this sort of size, although I suspect it's probably a good deal more expensive than heating insulation (which doesn't have to be closed cell).

If the OP wants cheap you can always use cardboard. Just be sure to secure it with something that will last, ie wire not sellotape.

NT

BES

sell armaflex foam lagging in imperial sizes for microbore pipes (intended for air conditioning). It's quite expensive (about 60p/m). They also do an armaflex 'bandage'. What I used in my house is the old style felt tube lagging (it has a polythene liner as well). It costs about 10p/m. It's actually big enough to take a much larger pipe, but that doesn't matter - you could lag two 10mm pipes next to each other in one go. The insulation level isn't quite as high as foam, but it's far better than nothing. I've also used a bubble wrap and aluminium foil insulation in one section, but it's quite expensive stuff.

-Antony