The Balloon

If tires are the contact point between your car and the road, the balloon is your contact point between your balloon and the sky.  Just like you shouldn't cheap out on tires just to save a buck, likewise you shouldn't go find the cheapest balloon.  In my opinion there is only one place to buy them, Kaymont.  (http://kaymontballoons.com/).

Here is my logic.  There are a lot of balloons available for a little less on ebay, and you can even find surplus balloons on there too.  Other suppliers are out there such as ScientificSales (http://www.scientificsales.com), but no one runs through as many balloons as Kaymont.  No one.  They are the major supplier for most of the government agencies that are constantly sending out sounding balloons.  This means their inventory is constantly fresh and turning.

Why would that matter?  Two words:  Natural Latex.

The balloons we are working with are made of natural latex, and thus will age.  With age comes undesirable characteristics, most of which will limit the eventual height of your balloon's flight.  If you are trying to get as high as possible, getting a fresh balloon and storing it properly (cool, dark places) should be of high priority.  What fun is it to go to all the effort and have the balloon just blow out while you are inflating it?

I also bought two balloons so I had one as insurance.  Things happen, and with all the time and energy going into this project, I would feel like an idiot blowing out the balloon and not having a spare.

I would also note that I have seen on just about every reference site I have looked at that you need to wear gloves when handling the balloon.  For some reason your body oils are the devil on these balloons, and so you need to take efforts to keep your hands covered.  I would think nitrile gloves would be fine, there shouldn't be any reason you have to use latex gloves.  The real issue is getting your oils on the balloon (or so the story goes) so go with whatever is cheaper or more readily available.

Balloons are purchased by weight.  It appears that the defacto standard size for High Altitude Ballooning are 1200 gram balloons.  Expect to pay around $100 for these.  I was able to get a holiday special that brought both balloons to about $175.

I looked at going with a 1500gram balloon, but in discussing the use of hydrogen they were recommending I go with a smaller 1000gram balloon.  More for ground safety than anything.  In the end I compromised and went with the 1200 gram balloon.  This should take a 4-6lb package to 100-105,000ft.

When they come they look like a rectilinear lump of bread dough in a clear plastic bag about the size of a small lunch box.

We will see what happens.