man applying calk to window

An unsung hero of home improvement, caulk is a hardworking essential for any homeowner. From sealing around the bathtub to filling in spaces in quarter-round or molding, a good caulk job comes in handy all throughout the house. Its usefulness results from its transformation from a goolike substance during application to a hardened seal that perfectly fills cracks. Caulk serves the critical job of keeping water and air away from where they don’t belong, saving expensive and time consuming mold repair and keeping your energy bills low. This seemingly simple task can prove complicated if you fail to prep yourself with basic knowledge before starting the project.

Before you drive to your local home-improvement store, you’ll need to consider the various types of caulk, their purposes and tools you’ll need. Then read on for a step-by-step guide to application.

Types of Caulk

Choose your caulk based on what it will adhere to and what you’re trying to keep from invading the space. The most common types of caulk are:

Acrylic Latex (Painter’s Caulk)
Commonly found around windows, doors and moldings, this type of caulk can be painted and comes in a variety of colors. It’s one of the least expensive caulks but only meant to cover cracks and small holes and then be painted over; perfect for your bathroom window, but not suggested for wet areas (like your tub).

Vinyl Latex
Easy to apply and clean up, like acrylic latex, but heavier duty and longer lasting. This type of caulk can be used outdoors but doesn’t expand and contract well with temperature changes. 

Acrylic Tile Sealant
Have you noticed those itty-bitty tubes of caulk that you squeeze by hand? This kind of caulk is meant for small spots and repairs in wet areas, and is typically resistant to mold and mildew. Be aware that tile sealant isn’t intended to last forever in frequently used areas like showers and tubs.

Pure Silicone
This type of caulk is also mildew- and mold-resistant, but unlike acrylic tile sealant it will last a long time on nonporous surfaces like tile glass and metal. It can be messier to apply and requires solvent to clean up (wear disposable gloves if you choose this one) but can last for decades. Silicone caulk smells strongly during application and while curing, so be prepared to ventilate until it’s dry. It can be difficult to remove and repair, because silicone doesn’t stick to itself, so for spot repairs, try acrylic tile sealant. 

Kitchen and Bath
This descriptive name tells you just what you need to know! This caulk is designed for high-moisture areas, comes in a variety of colors and resists mold and mildew. Let it dry thoroughly before you get it wet, and cleanup only requires soap and water. 

Pro Tip: When trying to decide what quantity to purchase, get a bit more than you think you’ll need so you don’t run out in the middle of application. Most stores will accept the return of unopened caulk, so it’s safer to have some extra on hand.

Tools You’ll Need

  • Enough caulk for the job
  • An appropriate caulk gun with piercer and built-in cutter
  • Caulk-removing tool (if needed)
  • Caulk-smoothing tool
  • A dry, clean cloth
  • Painter’s tape or masking tape 
  • Soap or mineral spirits for cleanup

Special tools can be purchased that make caulk application easier and more efficient, including dripless caulk guns, putty knives and smoothing tools (mentioned above). Caulking guns come in a variety of price ranges, from a few dollars to several hundred for battery-operated versions. Aim for one that features a seal punch, cutter (for trimming the tip of the tube) and dripless operation, which you should be able to find for about $20. 

Application

Once you’ve gathered your tools and materials, follow these application steps:

  1. Clean the surface by removing any old caulk or dirt. Wipe the surface clean with a dry cloth and apply masking or painter’s tape to create a clean edge that will prevent the caulk from adhering where it shouldn’t be.
  2. Prep the tube by cutting the nozzle at a 45-degree angle only as wide as the gap you wish to fill (the farther up the tube you go, the larger the amount that will come out). There will be an inner seal that must be pierced (be careful!) before you insert the caulk tube into the gun.
  3. Fill the tub with water (trust us), so the tub is heavy and as far from the wall as possible. Even this tiny space will create an even more perfect seal. Feel free to wear rain boots while you stand in the tub.
  4. Apply by squeezing with consistent pressure to control the flow rate of the caulk. 
  5. Within five minutes of application use the caulk-smoothing tool (or your finger) to smooth the caulk. Apply and smooth it in sections to prevent drying before you’ve had a chance to smooth the surface.
  6. When you’re finished, replace the cap on the caulk tube, remove the tape and wash your hands. Clean and tidy up the area around the caulk using soap and water for acrylic and mineral spirits for silicone.