Caulks

Caulks, or caulking compounds, are sealants used to fill gaps and joints to prevent the passage of air, moisture, and pests. They are commonly applied around windows and doors, sinks and tubs, baseboards, countertops, and exterior siding. They provide a flexible barrier and can also accommodate a degree of movement between substrates. Application is typically done with a caulking gun or by hand.

The main families of caulks are silicone, polyurethane, and acrylic latex. Silicone caulks are highly flexible and water resistant, making them popular for bathrooms and exterior work. Polyurethane caulks are strong, adhesion versatile, suited for exterior substrates and rough joints. Acrylic latex caulk is paintable, easier to work with, and often used indoors, though less durable in wet areas. Some products combine features, such as paintable silicone or siliconized acrylic.

Preparation and curing: surfaces must be clean, dry, and free of old caulk. Cut the tube tip to size, apply with a caulking gun, and smooth promptly with a finger or tool. Curing times vary by material and temperature; many caulks form a skin within 12–48 hours and reach full cure in several days. Avoid exposing to water until fully cured.

Maintenance: caulks should be inspected periodically for cracking, shrinkage, or mold growth. Damaged caulk should be removed and replaced. Environmental factors such as UV light, temperature cycling, and joint movement influence lifespan; typical exterior caulks last several years, interior variants shorter.

Safety and environmental considerations: some caulks contain solvents or isocyanates; use in well-ventilated areas and wear gloves. Look for low-VOC formulations when indoor air quality is a concern.