Implantable layers and methods for modifying the shape of the implantable layers for use with a surgical fastening instrument

A method for altering a tissue thickness compensator for use with a surgical instrument, said method comprising the steps of:

• obtaining a tissue thickness compensator comprised at least partially from a material including a glass transition temperature and a melting temperature, wherein said tissue thickness compensator comprises a first shape;
• heating said material to a temperature higher than said glass transition temperature and lower than said melting temperature;
• applying a modifying member to a tissue-facing side of said tissue thickness compensator;
• manipulating said tissue thickness compensator with said modifying member to a second shape different than said first shape by inducing a localized change in a portion of said tissue thickness compensator in contact with said modifying member;
• allowing said material to cool below said glass transition temperature;
• and
• releasing said modifying member from said portion of said tissue thickness compensator.