I hope someone here can help me with instructions for a knot.
A few years ago, a guy showed me what he called an 'Iron Knot'. It
will hold any weight, even up to the breaking point of the rope, but
when the tension is released the knot comes apart. Useful for lowering
buckets off a roof for example. When the bucket lands on the ground,
the knot falls open and you can pull the rope back up.

It was practical and elegantly simple. And I forgot how to make it
before I made notes.
I'd be grateful for any help so I can stop kicking myself.

Best, and thanks,
DB.