caulking

noun

A sealing material used to seal joints between heterogeneous materials in many kinds of construction and manufacture.
“Oakum was used for the caulking of the hulls of wooden ships.”
“Marina's bedroom was a small charming room with small charming windows of aged glass, dating to the mid-1800s, windowpanes badly in need of caulking, overlooking St. Agnes Roman Catholic Church with its heraldic spire floating on the night sky, and its ancient bumpy churchyard.”
An act/process of sealing using this material.