What Type of Caulk Dries Hard?


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Worker's hand using manual cartridge gun, glue gun, silicone tub

Caulking is an essential part of home construction and improvement, and it keeps an area dry and prevents water from leaking to areas it shouldn’t. As such, caulking is an integral component of the bathroom. A quick look at your local hardware store will reveal the multitude of caulk options available. The most common question regarding caulk is which one dries the fastest and dries hard. 

When it comes to the most recommended fastest drying and hardest caulk, that recognition goes to polyurethane caulk. There is a reason why polyurethane caulk is the recommended option for sealing driveways as it is the most durable option. 

Besides polyurethane caulk, the most commonly used caulk is acrylic latex with silicone. The popularity of the acrylic silicone caulk stems from it being a longstanding staple in this market and the most affordable. 

An Introduction to Polyurethane Caulk

The polyurethane caulk is durable, moisture, and corrosion-resistant adhesive comprised of glycol and isocyanate. These two compounds are mixed beforehand to create the polyurethane caulk. As noted earlier, the poly caulk is a highly durable and heavy-duty adhesive, sealant and caulk. Its incredible durability is why it is the caulk of choice in driveways that will require outstanding durability to support immense weight regularly. 

The application of polyurethane caulk is also relatively simple and easy as it is compatible with the caulk gun. Another great aspect of polyurethane caulk is that despite its excellent durability, it is surprisingly flexible. This is crucial in caulk as a building’s joints expand and contract throughout the year. A caulk that lacks flexibility will most likely leave it cracked and damaged sooner rather than later, and this is not the case with a polyurethane caulk. 

There are two variations available for the poly caulk in the market. The first is the industrial-strength version which requires mixing before being applied. The other is the commercial version with its ready-to-use form, which also needs mixing but does not require as much precision in care as the industrial version.  

Choosing the Right Caulk for a Specific Project

Generally, the silicone caulk will be more than enough to handle your joint sealing needs. That said, silicone caulk does have its shortcomings. The biggest drawback of using silicone caulk is that it’s very tricky to paint, which is not the case with polyurethane caulk. Therefore, if you plan on painting over the area where you applied the silicone caulk, you will need to do some extra steps first to be compatible with the paint.

When to Use the Polyurethane Caulk?

Polyurethane caulk is best used on wood or surfaces that will require painting afterward. Also, note that while polyurethane caulk is quite durable, it cannot withstand high UV exposure from sunlight as much as silicone caulk. However, in most cases, you can expect the polyurethane caulk to last for up to ten years, given that it has minimal exposure to sunlight. So, at the minimum, a polyurethane caulk can still last for up to five years. 

Another notable advantage of polyurethane caulk is that it is far easier to clean than other caulk types. Unfortunately, it will also dry within 24 hours, and once wholly hardened, will be incredibly difficult to remove. 

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