I want a balloon to "pop" at the touch of a sharp knife. Storing a ballon to optimum stretch inside a cake?

I made 1 excellent exploding cake with a balloon. I haven't been able to replicate the event as successfully. I need the balloon to be maximally inflated, to the point it will go "pop"! when the merest touch of a sharp blade touches it. Also if the balloon is concealed inside a whip cream, cake combo, does hot or cold temperature affect the expansion of the balloon? Is there anyone out there who has experience, or can solve this dilemma for me?

sort by: active | newest | oldest
qwertyman108 years ago
If you inflate it to maximum then hit it VERY lightly with a blowtorch, then blow it up more so its thinner. Or: Baked Alaska! :P
canida8 years ago
My guess is that you've been buying thicker balloons. The temperature change is likely to produce minimal effects unless you're using an ice cream cake or very cold whipped cream, so the primary variable is simply the type of balloon you purchase. Grab a few different types at the store, and pre-test!
Don't use cake at all. It's too dense for this. You need some cardboard, tinfoil, THICK whipped cream or an icing of about the same consistency, and some light decorations. Inflate your balloon until it's nice and firm and stretched thin. Hopefully you've selected a balloon that's the right size for your project... but to make sure I suggest you buy an assorted-package when shopping for them. Make a rectangular tray large enough for the balloon to rest on, plus a few inches each way. Wrap the tray in tinfoil. This is now your serving tray. Out of cardboard and tape, form a ring large enough to fit around the balloon snugly. It should be roughly 1" shorter than the balloon. Place the balloon and cardboard ring on the serving tray, using tape. You should now have a roughly circular cake with a round, bulging balloon-top. Now decorate. Ice the cake. Serve with the sharpest knife you have.
kelseymh8 years ago
PV ~ T, so if the pressure is constant, the volume is proportional to the absolute (kelvin) temperature. Use as small a balloon as you can find, so that the material is maximally stretched (and the pressure is highest).
Translation: cold stuff makes the balloon less likely to pop so easily.
The translation ought to be "cold stuff makes the balloon smaller," in response to Guest's embedded question, "does hot or cold temperature affect the expansion of the balloon." However, you are quite correct that a cold balloon will be less likely to pop, since the volume will be smaller and consequently the rubber less stretched.
Haha, your clarification is a third longer than the original statement I simplified!