How long did it take for the 56 signers to sign the declaration of independence?

I have never read anything concerning a time frame about the signing. Just from the written thoughts and descriptions my guess would be 20-30 minuted. Ben Franklin may have held things up a bit because he did like to point out the importance of events. It is reported he said, as he signed, "we need to hang together or we will hang separately." He was right. The king considered them traitors.