4. An old utensil which was used by a gentile must be kashered by either Hagala (purging in boiling water) or Lebun (being heated red in a fire) before being immersed.
5. A utensil rented or borrowed from a gentile need not be immersed. (If a person borrows or rents utensils from a Jewish merchant [who purchased them from a gentile], he should immerse them without a blessing. The merchant should later inform the subsequent purchasers of these utensils, lest they immerse them a second time with a blessing.)
6. Glassware produced by gentile workers in a factory owned by a Jew should be immersed without a blessing being recited.