Like many people, my first experience with caulk was in my bathroom. I noticed that the caulk around the tub was getting grey and peeling away from the tile. Without thinking too much, I went out and bought a tube of caulk to “fix it”. It didn't cross my mind that I should research how to caulk. I got home and removed the old damaged caulk fairly easily, and assumed applying the new caulk would be just as easy.
Within 30 minutes, my project was done. I only had a few drips to clean up and the bead was fairly smooth, with only a few lumps. Little did I know that within a few months the caulk would start to turn grey again. I've learned a lot since then.
The quality of your caulking job is based on doing the right prep before applying new caulk. Make sure the temperature and conditions are right for application. Check the label for the correct working conditions.
How to Caulk 1: Removing Old Caulk
Before you can make repairs, the old caulk needs to be removed. Silicone and polyurethane will not bond to itself and have to be removed completely. With latex and rubber based caulks, you can remove just the damaged or failing area before adding new caulk … but I feel more comfortable removing all of it.
There are lots of tools available that are geared to removing caulk and smoothing out the new caulk. You can also use a painters 5-in-1 tool, utility knife, scrapper or narrow chisel to remove old caulk. The key is to find a tool that you'll be comfortable holding for a long time and consider the position and pressure you'll need to exert. When scraping, be careful not to damage the surface you're removing the caulk from, as this may allow water to penetrate.
How to Caulk 2: Clean the Surface
After you've removed the old caulk or if you're adding caulk to an area that didn't have any, thoroughly clean the area. Any dirt or grime left on the surface can cause the caulk to fail. Use a soft brush or vacuum to pick up dust and debris. Rubbing alcohol will remove soap scum. If there are signs of mold or mildew, treat the area with a bleach solution. If you use a cleaning solution, follow up by rinsing with clean water.
Be sure to allow the area to dry completely before applying the caulk. You can use a hair dryer or a fan to speed up drying. Just like painting, caulking should be completed no more than one week after washing the surface to prevent organisms from growing again.
Step #3, Are You Ready to Caulk?
To help keep the area clean, put down newspaper to place the caulking gun on when you're not using it. You can mask off areas with painters tape to protect them and this will help produce a clean even edge. Prepare a small container with water (for water-based caulk) or the solvent used for cleaning and plenty of rags. This will help to clean drips quickly.
Step #4, Ready to Apply the Caulk?
Before you can use the tube of caulk, you need to cut the tip of the tube. Use an angled cut and make the opening slightly smaller then the bead you want to apply. You also need to puncture the seal inside the tip.
Use constant pressure and keep the caulk gun or tube moving at a steady pace to produce an even bead. Try practicing on a piece of cardboard to get the hang of it. When you come to the end of a bead, remember to release the pressure on the gun to prevent a lot of caulk from oozing out when you're not using it.
When you have a long bead to apply, don't be afraid to break it up into smaller sections. You can tool the section you just finished, then tackle the next section. Make sure to complete the whole run before taking a break. Some caulks won't stick to themselves once they have started to dry.
Smoothing the Caulk, Step #5
Tooling is the process of smoothing out the caulk so there are no bumps or lumps. You can use your finger dipped in water to smooth out water based caulk, or wrap your finger in an old damp t-shirt. Caulks that use a solvent for clean up can be smoothed using a plastic spoon.
You can use rubber tools such as the one shown above, and they come in several shapes to fit your requirements. You simply snap the tip you want onto the end of the caulking tool. If you used painters tape, remove it after you finish tooling, or you risk tearing out the caulk you just patiently installed.
Caulking Tips for DIYers
Here are a few tips to help you get a professional looking caulk job.
- If you're getting ready to paint, caulk before applying your finish paint. When you're working with new wood, prime it before caulking.
- If you're using a stain or clear finish on wood, you'll want to use wood filler between wood joints and the same to cover nail holes. A clear or color matched caulk around door and window frames will help make the caulk “disappear”.
- Ideal temperature for caulking is 45and 80 degrees Fahrenheit outdoors and dry.
- Gaps bigger then 1/4 inch will need a backer rod to help fill the gap. Then you can apply a standard caulk bead.
- When you're done, don't forget to clean the tooling tools. If your caulk didn't come with a cap, a 16d nail inserted in the tip will help prevent the caulk from hardening, which can make the rest of the tube unusable.
- You can also watch this short video for a few more important tips … from a pro!
- If you want to know how much you'll need, measure the areas to be caulked, add them all up, then go to this cool calculator to figure it out!
Check out other articles we have on caulking, an important task in preventive home maintenance:
- How to buy the right caulk, read Caulking Basics: How to Pick the Right Caulk.
- To figure out which caulk to use, read Caulking – How Many Types are There.
- Tips for homeowners who want to learn to caulk, Learning How to Caulk (this article).
- For more on home maintenance, read Where & Why to Caulk Around Your Home.