Just a little review of my research about the balloon material.
Theoretically, we have two options : we can either do it ourself, or buy latex balloons. The second solution seems better.
Doing some homemade handcraft sounds hazardous : I have a really unclear idea of the material (survival blanket, transparent bin bag ?) or the technique to use, the scotch or whatever we use will be heavy, and we will spend our time sealing leaks … One the other hand, buying a lot of balloon has a cost. And not every kind of size/color/material can be found.
A few models that could fit us :
- Qualatex : Clear Deco Bubble (24”/61cm) [http://www.amazon.com/Clear-Deco-Bubble-Qualatex-Balloons/dp/B0060RDT96]
- Qualatex : Chloroprene Giant Cloudbuster (48”/120cm) [http://www.balloonplace.com/catalog/Qualatex_latex.html# rechercher:cloudbuster]
- Qualatex/Sempertex : Latex Round Balloon (36”/90cm) [http://www.ventedeballon.com/ballon-latex-rond-90cm-sempertex-blanc-005-xml-252_262_406-4157.html]
We also have to know that such balloon filled with helium will stay filled 2 days maximum. We can improve that by using some kind of float extender product (http://issuu.com/pioneer1/docs/2013_pel_catalogue?e=4272177/1511762 page 140), but it also has a cost.
Last thing to conclude that post : Helium. Expensive (~20e/m3). Haven’t decide yet which kind of supplier we will buy from.