unfasten vs unstop

unfasten

verb
  • To detach from any connecting agency or link; to disconnect. 

  • To come unloosed or untied. 

unstop

verb
  • To remove a stoppage; to clear a blockage. 

  • To draw out the stops of (an organ). 

  • To unplug or uncork a container. 

How often have the words unfasten and unstop occurred in a corpus of books? (source: Google Ngram Viewer )