Back in black

Black Caulk: Don’t judge a caulk by its color

Black caulks form durable and flexible seals that are ideal for a range of joints in your home. Their weatherproof, waterproof seals can withstand harsh conditions and are designed to last as your building materials move and age.

The low-down on black caulk

Black caulks can bind, fix, and seal most exterior building materials because they are flexible enough to accommodate the natural movements of construction materials. Plus: high-end black caulks will not sag. These sealants are available in many formulas resistant to corrosion, tears, and weather, such as black acrylic latex caulks and black silicone caulks. Most black caulks emit little odor, and many require no primer, making them relatively easy to use.

When to use black caulk

Because they form durable seals that remain flexible, you can use most black caulks for many heavy-duty exterior and several interior applications. Some black caulks, such as black grout caulk, are formulated for specific purposes. It is worth noting that product names often do not contain the term “black caulk.” 

For example, Loctite PL Roof and Flashing Polyurethane Sealant is a premium black exterior caulk designed to seal roof flashing around chimneys and roof edging. You can also use Loctite PL S30 Polyurethane Roof and Flashing Sealant for shingle tabbing and covering roofing nails. It is ideal for a variety of substrates that include metal, brick, concrete, and stucco.

How to use black caulk

Gather materials. Get your caulk, a utility knife, and a caulking gun. Wear gloves.

Prepare surfaces and joints. Surfaces must be free of contaminants and residue, and structurally sound. Your sealant depth should generally be half of your joint width; most products’ maximum sealant depth is ½ inch or less. Use a backing rod for deeper joints.

Even black caulks which are generally considered non-priming sealants may require a primer for special substrates or under certain circumstances. Check your product’s adhesion to a test joint before ruling out primer.

Prepare caulk. Place your black caulk in a caulk gun after completing preparatory work. Puncture or cut the nozzle at an angle to the proper bead size.

Apply caulk. Exerting steady pressure, apply black caulk to the seam from the deepest point to the surface by holding the nozzle against the back of the joint. Observe safety information in the manufacturer’s instructions.

Tooling. Tool the black caulk within the recommended time period and using the solvent stated in the instructions. Tooling gives you the correct bead shape, a clean joint, and maximum adhesion.

Clean up. Clean tools and any black caulk residue using the solvent listed in the product details. You can carefully cut away excess cured caulk using a sharp-edged tool. Wash your hands when you are finished.