A caulker is a general-purpose spreading tool with a wide handle and flexible blade.
A brief history of caulkers…
The first caulking tools were used to seal the seams on ships in order to make them watertight.
In later years the term ‘caulking’ came to mean any form of sealing of joints or seams in various structures, buildings and even some types of piping.
In its modern context, ‘caulking’ refers to the application of flexible sealing compounds to fill gaps in buildings and other structures from air, water, dust, and insects.