If you are planning to renovate your own home or build something new from scratch, one of the things that you are going to need to know all about are sealants, particularly when it comes to sealing your various fixtures from the elements. Yes, here we are talking about that caulking around your bathtub, sink, faucets, and so on.
Now, if you are planning to do your own sealing, it is important that you choose the right kind. Two main types out there include polyurethane caulking and silicone caulking. Today, we are going to figure out exactly what both of these are, what similarities they share, what the differences are, and which is best for certain applications.
Polyurethane and Silicone Caulk: The Basics
Before we get into talking about the shared similarities and the differences between polyurethane and silicone caulk, let’s first figure out exactly what both of them are.
What is Polyurethane Caulk?
What you need to know here is that polyurethane is a material of itself, an organic compound to be specific, one created by the reaction between glycol and isocyanate.
However, without getting too deep into the science of it, what you need to know here is that when polyurethane caulk is exposed to the air (when it comes out of the tube), there is a chemical reaction that occurs, which causes it to cure and harden. Now, the main point to keep in mind here is that polyurethane is organic, or in other words, it comes from nature.
Polyurethane in itself is durable, moisture resistant, and corrosion resistant, which is why it is used as a caulk, sealant, and adhesive. This type of caulk is most often used for repairing cracks in masonry, sealing concrete control joints, repairing cracked vinyl, caulking around windows and doors, and more.
What is Silicone Caulk?
Silicone caulk is another type of adhesive sealant that is often used to prevent both air and water from passing through certain locations, such as gaps between masonry or the space between your tub and the wall.
Now, what is very important to note here is that silicone is not an organic material, unlike polyurethane. For those of you who don’t know, silicone is a polymer made of siloxane, which is usually colorless oils or substances with properties similar to rubber.
Similarities of Polyurethane and Silicone Caulk
Alright, so now that we know exactly what both polyurethane and silicone caulk is, let’s figure out what similarities they share.
#1: Both Are Used as Sealants
Ok, so the most basic similarity that both of these materials or types of caulking share is that they are of course used as sealants. After all, using polyurethane or silicone caulk as sealants is what we are here to talk about today.
#2: Both Are Applied the Same Way
Another very basic similarity that both of these types of caulk share is that they are applied with a caulking gun. Both come in a special tube that fits into a caulking gun for easy application.
#3: Both Need to Stay Dry While Curing
The third and final basic similarity that both of these types of caulk share is that they both need to stay dry while they cure and harden. Generally speaking, both may take up to a full day or even longer to achieve a full cure.
Differences Between Polyurethane and Silicone Caulk
With that out of the way, let’s take a look at the differences between the two. These will, naturally, be the main decision-making factor affecting your choice of one or the other.
#1: Silicone Caulk Handles Cold Better
One of the main differences that you will find between silicone and polyurethane caulk is that silicone caulk handles the cold much better. Polyurethane caulk dries hard and can become very brittle in the cold, and eventually crack. Silicone caulk dries relatively flexible and remains flexible, and plus, it also doesn’t harden or become brittle in the cold, therefore making it the better choice for cold temperatures.
#2: Silicone Caulk Is More UV Resistant
Things that are organic are automatically susceptible to UV damage, or in other words, polyurethane caulk doesn’t do so well outdoors when exposed to lots of sunlight. It can become quite brittle over time and eventually crack, peel, and just totally come off the surface. This is not something that will happen with silicone caulk, as it is not susceptible to UV damage.
#3: Polyurethane to Wood, Silicone Does Not
Something that you need to be aware of here is that polyurethane sticks to almost everything. It will even stick to wood, although it will not stick to very smooth plastic. Silicone caulk, on the other hand, sticks to everything but wood, so you cannot use it for wood sealing purposes.
#4: Silicone Caulk Will Last About Twice as Long
The simple truth here is that silicone caulk is much more moisture, UV, and temperature resistant than polyurethane caulk, and it also forms a stronger bond, which is why it will last for up to 20 years, whereas with polyurethane caulk, you’d be lucky to get ten years out of it.
#5: Silicone Caulk Is More Expensive
With all of the benefits that silicone caulk has over polyurethane caulk, it is also about twice as expensive.
#6: Silicone Produces More Fumes and Odors
When it comes to working with these products, polyurethane caulk doesn’t produce quite as many noxious fumes as silicone caulk does. You could get away with using polyurethane caulk without a face mask, but when using silicone caulk, a respirator is recommended.
#7: Silicone Caulk Dries Flexible, Polyurethane Does Not
A big advantage that silicone caulk has over polyurethane caulk is that it dries flexible, which makes it ideal for areas that experience movement and contraction. Polyurethane dries rock hard, and while it does form a strong bond, contractions and movement in general will cause it to crack and come undone.
#8: Easier Clean-Up for Polyurethane Caulk
Polyurethane caulk can be cleaned using mineral spirits, whereas silicone caulk needs to be removed using a special silicone solvent.
#9: Polyurethane Caulk Can Be Painted
The other main difference here is that you can paint over polyurethane caulk, but you cannot paint over silicone. Paint will not adhere to it at all.
Polyurethane vs. Silicone Caulk: Which of the Two Should You Use?
Ok, so if you are sealing corners between walls and between ceilings and walls, and it is for indoor use, then polyurethane caulk will do just fine. If you are working with wood, it’s indoors, and there are no moving parts to be connected, then polyurethane is fine.
However, if you are sealing anything to do with moisture, such as bathtubs and bathroom tiles, if you are working outdoors, or if there are moving parts, then it is silicone caulk that you want to use.
Summary
The bottom line is that while polyurethane caulk does have its uses, if you are working outdoors or with anything that involves moisture, such as in your kitchen or bathroom, then it is silicone caulk that you want to go with.