Bring water and salt to a slow boil, cook corn in batches, boiling for 4 minutes each batch.
Transfer cooked ears to a dish towel, allow to drain and cool until easily handled (this is how you keep the corn from being too watery).
Using an angel food cake pan, place ear on center and begin cutting kernels off so they fall into the pan. Then angle knife slightly to get the small bits out of the ears. Repeat until pan is full or all ears are cut.
Pour butter over kernels and mix well (this gives each kernel its own seal).
Put about 2 cups of corn into individual bags. Squeeze all the air out, seal then push to flatten each bag.
Freeze flat on a cookie sheet to keep each bag flat, then stack to store in freezer.
Corn will be good for up to a year, to use, defrost in the microwave and serve.