Caulk vs. Sealant
Before going a step further, you might have heard caulk called a sealant and vice versa. Technically, the two serve the same purpose—sealing a space, making it airtight or waterproof. But there is a significant difference between them; sealants are used on objects that shift or move, like windows, for example. A sealant is used when you need more elasticity so it can shift with the moving object it’s sealing. Meanwhile, caulk is best suited for filling the space where the shower tiles meet the top of the bathtub—both surfaces are stationary. Also, caulk’s significant benefit over sealant is that acrylic latex can be painted on, while sealant can’t.
Types of Caulk
Caulk comes in many options: different colors, fast-drying, and sanded vs. unsanded. Sanded, grainy-textured caulk works best sealing wet spaces and large gaps of 1/8-inch or more. Unsanded has a smooth texture and appearance, working best on kitchen countertops and backsplashes. Caulks are water-based, like acrylic or latex, or solvent-based, like polyurethane, silicone, or butyl rubber. Solvent-based caulks require mineral spirits or other strong solvents to remove them, while acrylic and latex products do not. Also, you can get caulks that are a hybrid like silicone and polyurethane combined. Here’s an overview of some of the main types of caulk and their different uses. Use this caulk for filling small gaps and blemishes in wood trim and for sealing joints between wood parts that you will paint. While the label may claim it’s suitable for wet areas, it’s best to stick to dry areas or on parts that may see moisture (like exterior trim and siding) but will be protected by a complete coating of paint. While this caulk is commonly called “tub and tile” caulk, it’s not as good as pure silicone for tile and bathroom fixtures. Use pure silicone for sealing around plumbing fixtures, such as sinks, toilets, and faucets, and for any caulk joints on the tile in wet areas. It’s also a general-purpose sealant and waterproofer for holes in exterior walls, sealing around pipe and wiring penetrations, and filling gaps between exposed materials of almost any type. Finally, pure silicone is a pretty strong adhesive and can be used as glue for under-mounted sinks or fixtures attached to stone and other hard-to-glue materials. Silicone will work on roofs and windows or doors, but it’s not the best option for those applications. Instead, use a high-quality roofing sealant for roof work, and use a high-quality window and door sealant (not latex caulk) for installing and sealing windows and doors. (It lasts as long as silicone and is paintable.)
