stickum vs unstick

stickum

noun
  • Any adhesive, adhesive residue; any sticky or gummy substance. 

unstick

verb
  • To free from the condition of being stuck. 

  • To leave the ground during takeoff. 

  • To become freed from a stuck condition. 

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