Can Caulk Shrink?

Nov 6th 2020

Applying caulk is a relatively simple process when you know what you’re doing. Nevertheless, even those with the most enviable experience might struggle if conditions are less than ideal. For example, many people are unaware that caulking can shrink. It can, so it’s important to lay your caulk lines correctly the first time in order to prevent having to lay a new line over one that has shrunk.

Why Does Caulk Shrink?

To answer this, knowing what caulk is as a chemical compound is a good start. Caulk is not like paint, and leaving it for a few hours to allow it to become solid is not technically “drying” your caulk. Caulk is a chemical mixture that “cures” rather than dries, and despite the two sounding like similar processes, there is a difference.

  • Drying- when a solvent (usually water or moisture) evaporates from the coating of an object
  • Curing- drawing out the moisture in an object via osmosis and allowing that object to obtain ideal hardness

Because curing removes moisture to obtain hardness, caulk lines shrink because the water molecules that were once a part of the mixture are no longer present, making the caulk decrease in mass, width, or length.

Shrinking Prevention

First, some shrinkage is not a big deal. It’s a normal part of the curing process, and having a slightly concave line of caulk means that it has properly hardened and will maintain elasticity for when it needs to stretch rather than tear. If you want to prevent your caulk line from shrinking from the start, apply your line slightly thicker than you want it to look. Avoid laying too thick a line; still, it should be thick enough to cure into an ideal width.

If you have already laid your line and let it cure, and you find that the bead is too thin for your liking, simply lay a second line atop the first. This way, the second line will cure and fill in the space that the first line left behind. Again, lay it carefully, so that you do not end up with a thick, bumpy line as an end result.

Caulking material is versatile, durable, and generally easy to use. Fortunately, it is also very forgiving when it comes to minor errors. Most caulking mistakes require a quick, simple fix and caulk shrinkage is one of them. For more high-quality products for all your caulking needs, visit Silicone Depot!