Related Program: Morning Edition on WEKU Polyester Strings Put More Spin On A Tennis Ball Related Program: Morning Edition on WEKU TweetShareGoogle+Email Great tennis legends used to use heavy wooden rackets. Graphite arrived about 25 years ago. Since then, the technology hasn't change much. That is until now. More and more pros are using polyester strings in their rackets. TweetShareGoogle+EmailView the discussion thread.