From an e-mail:
How to seal a bag and make it air-tight!
Cut up a disposable water bottle and keep the neck and top,
as in photo.

Insert the plastic bag through the neck and screw the top – to seal.

The bottle is made to be air-tight, such that water will not leak,
the secret lies with the top and screw!
Cut up a disposable water bottle and keep the neck and top,
as in photo.

Insert the plastic bag through the neck and screw the top – to seal.

The bottle is made to be air-tight, such that water will not leak,
the secret lies with the top and screw!