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 and 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. Moreover, high-end black caulks will not sag. These sealants are available in many formulas that are resistant to corrosion, tearing, 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 purposes 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 to cover roofing nails. This product is ideal for a variety of substrates that include metal, brick, concrete, and stucco.

If you want to paint your black caulk, read the product instructions to see whether your product is paintable. You should be able to paint most black acrylic latex caulks, but pure black silicone caulks can be problematic. Also check your product instructions to find out how well your black caulk reacts to application in moist areas and on surfaces subject to extreme heat. Last but not least, make sure the black caulk you want to purchase can bond with the materials you need to seal.

How to use black caulk

Applying different types of black caulk is pretty easy if you follow the basic steps outlined below.

  • Gather your materials. Get your black 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. The depth of your black caulk should generally be half the width of your joint; most products’ maximum sealant depth is ½ inch or less. Use a backing rod for deeper joints. Specific surfaces, such as masonry and wood, may require special preparation. If this is the case, your product instructions will provide the necessary information.

Black caulks that are generally considered non-priming sealants may require a primer for special substrates or under certain circumstances. Apply your product to a test joint and see how well it adheres to determine whether or not you need a primer.

  • Prepare the black caulk. Place your black caulk in a caulk gun. Puncture or cut the nozzle at an angle to the proper bead size.
  • Apply the 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 the safety information in the manufacturer’s instructions.
  • Tooling. Tool the black caulk within the recommended time period and using the solvent stated in the product instructions. Tooling gives you the correct bead shape, a clean joint, and maximum adhesion.
  • Clean up. Clean your tools and any black caulk residue using the solvent listed in the product instructions. You can carefully cut away excess cured black caulk using a sharp-edged tool. Wash your hands when you are finished.