just packed my camera away for repair in an large parcel envelope. After piercing it a couple of times it inflated to protect the camera. Any ideas how it does this? I tried googling but came up a fat zero.
Do you just pierce it wherever you want or is there a “pierce here” indication?
There is a pierce here instruction
Good. My WAG wouldn’t accomodate the other option. 
In piercing, you expose an agent to a reagent, which results in a chemical reaction which fills the bag with gas. Sorry I can’t be more specific, but it’s just a WAG.
WAG quotient of this answer: 82.7%
Here is my WAG: If you take some cotton or some other padding material, put it in a plastic bag and pump out the air, the padding will get compressed and almost flat. If you then poke a hole to let some air in, it will expand again. I think it’s the same principle.
They sell bags that work this way to store clothes. You put your winter clothes, blankets, futons, etc. in a big plastic bag and hook up a little pump. The bag shrinks to about 1/3 of the size, taking up less space in the closet. I don’t know if people actually use it, but they show it on infomercials in Japan all the time.
It’s simple. The walls of the envelope contain foam rubber that has been compressed flat and sealed inside an airless, airtight bladder. The foam rubber naturally wants to expand to its full size/shape but cannot do so because air cannot enter the bladder. By puncturing the bladder you are letting the air in. The walls of the envelope inflate as the foam expands.
Oh, wait. The envelope is padded? That was mentioned before.
So why is the “pierce here” instruction necessary?
I meant to say wasn’t, of course. :rolleyes:
I think you are probably right. I will take one of these apart tonite - but a casual inspection shows no obvious sign of a chemical or other blowing agent. Very cunning these envelope people
Please let us know what you find, scm1001, as there are several unanswered questions here.
Also, please inspect carefully for a patent number or manufacturer name. I’d love to look up the patent info on this.
Dear Kneadto know
the envelop is indeed vacuum powered, by Xpander Pak (www.xpander.com)
patents nos (US and foreign) 4,193,499 and 4,620,633
I should have guessed the vacuum bit, but my mind was thinking too high tech, with little gas cylinders etc
:shakes fist:
You’ve won this round, scr4 and stuyguy, but I’ll be back!!!
:husky gentlemen in white uniforms haul Knead away: