In my ongoing efforts to control my scent phobia, I've been looking into airtight bags for my gear. I just ordered a carbon suit, so I'm particularly interested this year...

In past years, I've used big ziploc bags and when I seal them, I purge the air out first. But a couple days later the bags are puffed up with air......Doesn't sound airtight to me.

SO.......I was at the local Wal Mart today, just killing some time really, and in the camping section I came across some watertight bags....They came 3 to a pack, all 3 different sizes. The smallest was pretty gosh darn small actually, but I guess it would work for socks and undies and such....But I digress.....You stuff clothes in, purge the air, roll the top and clip it shut....Now, after I did that I was of course curious as to whether it's actually AIR tight or not.....So, I squeezed that rascal as hard as I could and didn't notice any air leaking anywhere...

My question is, has anyone here used these bags before, and if so are they airtight? If not, what could be a "scientific" way I could test to see if they are or not? Any thoughts?