Fungus is right, but only freeze it for a couple of hrs then pack it. Also worked good for some antique levelwinds I wanted to preserve. During times of plenty it works great for preserving garden herbs
It does suck all the air out of a can. Bags are expensive. I have a Foodsaver and its around 10 bucks for 22 quart bags. The also have Gal bags and rolls where you can make a custom size.