As jojoebi pointed out in the comments section of the previous post, you cannot open the cans of caramel/toffee while they are hot. They must be completely cool. On the upside, you can make it far in advance and store the cans in your pantry. I'd do three at a time.
Again, the safety notes:
- cans must be completely covered with water the entire 3 hours they are simmering.
- DO NOT OPEN HOT CANS. let cool completely.
If you have a melty/caramely application that you want to use them for, I would take them out after 2.5 hours.
Also, I'd soak off the labels first. The label goo made a nasty mess in my favorite copper pot.