nonwashable vs unwashable

nonwashable

noun

  • Something that cannot be washed in the normal way without being damaged. 

adj

  • Not washable. 

unwashable

noun

  • Something that cannot be washed in the normal way without being damaged. 

adj

  • Not washable; that cannot be washed. 

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