What do you mean exactly by insulate the jar / tube?
Would plastic or something work?
Edit: What do you think about the box having a lot of airflow? Would that have any effect on the condensation?
The jar...
I've got a better example though, assume you have a cardboard box, with a tube running through it horizontally. The tube is carrying sub-ambient water through it and you don't want water to condensate on the tube (or anywhere for that matter) so that the box will became wet. Even a...
I'm not sure if this is the right section... But
Assume you have a medium sized box (about as big as a large desktop computer) inside a room.
And inside the box there is a jar of water that is significantly colder than the outside temperature.
How would you prevent water condensation...