what is caulk
Save. Caulk is a non-structural, physical compound that provides an airtight, watertight, or non-porous seal. The seal or closure made by caulk is used to prevent something, such as air, water, gas, liquid, or steam, from entering or escaping between two other materials.Caulk is used to seal joints or spaces between those two materials whether they are similar in substance or not.People have used caulk for centuries.hat It's Made Of. Caulk is made of materials that have been used for centuries and newer chemical substances created through the advances of modern science. You may recognize it in many forms such as the chinking used between logs on a log cabin to the rubbery substance that surrounds a shower enclosure.