Originally Posted by I Heart Thomas Muster
My friend CLAIMED his uncle used piano wire for tennis strings.
"Piano strings are among the most demanding of all applications of steel. Placed under high tension, they are subject to repeated blows, they are stretched and slackened during tuning and are still expected to last for decades."
Sounds like they hold their tension at least.
Metal wire, usually piano wire, was used in some historical racquets.