Hi Mal, your balloons probably were a bit old, they become porous with the years. But that is no problem, you just have to cook them a few minutes in boiling water (no joke!) and they are fine again
A friend of mine had a lot of success with (new) 1m dia latex ballons which a readily available. These are much lighter than met balloons. He got about a week out of each filling. However he was only
Hi All I got a couple of met balloons a while back and decided to inflate them for LF airborne activities but it was a big disappointment, although new they seem to be porous and the gas escaped with