[Mortalsfool]

My freeze is not frost-free. Why is frost in sealed packages? What causes it?

[Mortalsfool]

Why and how does frost get onto food in a sealed package in a freezer that is not 'frost-free'?

[drtom4444]

Water evaporates from the food and condenses on the colder wrapping.

[Mortalsfool]

Thanks DrTom for your answer. I assumed that the moisture came from inside the package, but what is the difference in the surrounding air that is different from a frost free freezer?
If the temp is the same in both freezers, why does one condence the moisture in the package and one does not? Something's up.

I have always been curious why.
Jack

[joypulv]

There's always moisture in the air in the freezer as well as in the food inside the package.
The frost free one is continually removing moisture and sending it down a little drip tube at the back to a pan where it evaporates (that's the usual method anyway). So in a sense frost is there, just not there long enough to show.

[drtom4444]

If a package is colder when put in a warmer freezer frost will form on the outside of the package, plus when the freezer goes into defrost it vaporizes some moisture and that condenses onto the outside of packages.