Stretching Rope of Prussia- Blue

The magician shows a short rope and a long rope and they suddenly become one long rope that is shown freely.
The rope is folded in half and the ends are pulled right off. The magician then shows the rope is now a loop.
Next, the magician shows the ends and replaces them back onto the loop making it a normal rope again.

The rope is held so that both ends are shown and the magician starts to pull on the rope and it begins to lengthen to three times the starting length.

CB