rubber stamp vs sealing wax

rubber stamp

noun
  • A piece of rubber or similar material with a design or text carved or molded for the purpose of transferring ink or dye to imprint that design on another object. 

  • A person or organisation that approves, routinely or as a formality, matters decided by some other person or organisation. 

verb
  • To process, approve or decide matters routinely rather than through careful consideration. 

adj
  • Of a person, organisation, or process, making decisions or approving matters routinely or without real power. 

sealing wax

noun
  • Wax formerly melted onto a letter to seal it; the picture of the sender's seal was often pressed into the wax as evidence that the letter had not been opened. 

How often have the words rubber stamp and sealing wax occurred in a corpus of books? (source: Google Ngram Viewer )