How to pronounce “unfastening” in English

"The first time he tried it he caught his coat-tail in it, and I had to walk around him with a pan of hot coals all night to keep him from freezing.' 'Well, why didn’t hetake his coat off?' 'Well, I wanted him to, but he stood around till the thing opened itself, trying to invent some way of unfastening it.""That’s William’s trouble. He will invent. A little while ago he got up a cabinet bedstead that would shut and open without handling. It went by clockwork. William got into it,