Caulk. Get a tube, stick it in a caulk gun, and squeeze. Simple right? Unless you know the basics it can get overwhelming fast. If you've started looking into one of your first caulking projects you've probably asked one or more of the following question - "What's the difference between acrylic and silicone caulk?", "Are they all paintable?", "How much should I use?", "How do I get professional looking lines?"... This post will attempt to answer these questions and give you the basic knowledge you need to feel confident the next time you're facing down a row of caulk shelves at Home Depot with a bazillion* variations of caulk.
*Bazillion isn't really a number. There were 128 results for caulk products on homedepot.com
Is caulk the right tool for the job?
First and foremost, let's make sure we're using caulk for what it was intended. Caulk is typically used to seal gaps/seams between many different kinds of building materials. Some projects are more cosmetic in nature (e.g. filling the gap between base molding and the wall/fixture) and others are more functional (e.g. sealing a seam between a bathtub and a tile wall to prevent moisture from entering the wall and causing rot). Caulk can be a great way to fill nail holes when painting a wall (assuming you use the right kind!). Keep in mind that caulk is not glue and glue is not caulk. If you need to adhere two things together that have opposing forces acting on them, make sure to use the appropriate adhesive product. If you need to fill a gap, an adhesive product likely won't provide a water-tight seal and doesn't have the same flexibility that caulk does that is required when dealing with shifting, swelling, and shrinking joints.
Should I use acrylic or silicone?
Acrylic caulk is typically used for indoor applications such as: around the door, window, and base and crown molding where it can be cosmetic, help prevent drafts, and where waterproofing is not necessary. Acrylic caulk is easier to cleanup than silicone, it is easier to "gun" (push through the tube and apply), it's typically less expensive, and it is easy to paint. However, acrylic tends to shrink and crack over time whereas silicone does not if applied correctly.
Up until somewhat recently, silicone caulk's primary function has been waterproofing. You'll typically find silicone caulk around exterior window, door, and garage trim, on corner joints of the house, and around holes where cables and wires enter a home (take a look at where your cable tv line comes in). Interior waterproofing applications include showers, bathtubs, sinks, backsplashes, and toilets. Silicone lasts longer than acrylic and doesn't peel, crack, or shrink the way acrylic does over time but it is typically more expensive. Up until relatively recently silicone caulk was not paintable. However, multiple manufacturers such as GE and DAP now sell silicone and silicone/acrylic blends that are paintable and have all the favored properties of silicone including its flexibility, resistance to cracking and peeling, etc.
Do I need paintable caulk?
I don't know, do you? Make sure to think about this because if you buy and apply non-paintable caulk and then later decide you want to paint it, you're SOL (look it up if you don't know it). For something like a seam between a kitchen counter and a backsplash, it's unlikely that you'd ever want to paint it but for a seam between base molding and a wall, you'll likely want to paint it unless both happen to be the same color as the caulk that you bought.
What If I Have a Large Gap?
If you find that you have large gaps, larger than the size of a reasonable caulk bead (1/2 inch or less) then you need a flexible backer rod. First put the rod into the gap and then fill the remaining space with caulk. If you try to fill a large gap without a backer, the caulk will most likely not adhere and you'll wind up with a messy, unsealed seam. See the last section for a link to a quality backer rod on Amazon.
I'm Replacing Old Caulk. What Do I Need to Know?
First and foremost you will need to remove the old caulk. Prep is the most important aspect of replacing old caulk. Take your time removing the old caulk this will ensure both the tightest seal and the cleanest, best looking application.
How long does it take to dry?
Drying time is dependent on the product but typically takes between 12 and 48 hours to fully cure. However, generally speaking, acrylic and silicone caulks both dry slower the colder the temperature. The higher the humidity the slower acrylic caulk dries because the curing process depends on water evaporation. On the other hand, silicone caulk dries slower in lower humidity.
Be sure to plan accordingly when caulking an area such as a shower that you'll potentially want to use soon. Some of the higher-end products can be exposed to water in as little as 30 minutes but others require 12 or more hours.
Which products did we use for our interior trailer renovations?
Personally, for the interior work we've done on our trailer, we prefer silicone products. Trailers are constantly flexing and often have to endure extreme weather conditions. The flexibility and longevity that come with silicone are worth the extra cost to us. That being said, we don't use the same product for all projects.
For the shower walls and basin we used a white, waterproof, mold-resistent, non-paintable silicone. For the bathroom sink and kitchen counter/backsplash we used a clear, mold-resistent, non-paintable silicone. And for filling holes in walls and gaps in molding we used a paintable silicone.
Depending on your project there might be better options but these are the ones that we used for the applications listed above and we have been very happy with the results.
What else do I need to complete my caulking project?
Caulking doesn't require a bunch of expensive tools and supplies but you do need a few things to do it right. Firstly you'll need at least one tube of caulk. Refer to the information above to choose an appropriate caulk. Secondly, you'll need a caulk gun to apply the caulk. Next you'll need a utility blade to cut the tip of the caulk tube applicator. For clean lines you'll want a roll of painters tape. If you don't want to use the best and least expensive spreading tool (your finger) you'll want to get a spreading tool. You'll also want to have some paper towels or rags handy as it's inevitable that you'll drop some caulk in unwanted places and you'll definitely want to wipe off your applicator as too much caulk accumulates. If you're replacing old caulk you'll want a caulk removal tool. If you have a large seam, be sure to first insert a backer rod.
- When cutting the tip of the nozzle always start with a smaller hole and enlarge it as needed. If you start too large there's no going back and you'll either waste a tube of caulk or end up with a messy job.
- Take the time to properly tape off the seams that you are filling. Make sure the tape is applied smoothly to the surface and is straight.
- Assuming you are using tape, carefully time the removal of the tape. If you don't wait long enough you'll pull the caulk along with the tape and make a mess. If you wait too long you may pull the caulk out of the seem depending on how much you got on the tape. There's a window when the caulk has started to set so it won't pull and stretch with the tape but it hasn't set enough to fully adhere to the tape and possibly pull out of the seam with the tape. We can't tell you when that window is it's highly dependent on the product, temperature and humidity but we have found that it's usually not too long after applying the caulk.
- Don't use too much. If you find yourself having to create a large bead or even go over a section more than once you're probably applying too much caulk. This likely means one of two things. 1) the gap is too large and you are not using a backer rod or 2) you're going to have a mess on your hands when you tool it into the seam with your finger or your caulk tool.