sponge out vs wash off

sponge out

verb
  • To remove by using a sponge. 

  • To clean the inside of (something) by using a sponge. 

  • To remove (something, especially debts). 

wash off

verb
  • To remove (or be removed) by washing. 

How often have the words sponge out and wash off occurred in a corpus of books? (source: Google Ngram Viewer )