Defrosting the Freezer

My freezer was in desperate need of defrosting so one day I took the plunge and cleaned it.

Chad and 'Shiny' helped me. We took all the stuff out and put it in coolers. Meanwhile I boiled some large kettles of water and unplugged the freezer. We set a kettle in the freezer on the middle shelf and shut the door. We laid towels around it on the floor and gathered up rags and buckets. After the steam did its work we traded kettles and shut the door again. In a short amount of time the freezer was clean!! (=

Wow! What a great feeling.
How often DOES one defrost a freezer???