Glazed vs Unglazed Porcelain & Ceramic Tile

What does it mean that ceramic tile has been glazed, and is it better that it’s glazed or unglazed?

Did you know there are also different types that you can choose that have different purposes and will leave a different finish?

In this article we’ll try to cover all the possible questions you may be having. If you’re in the process of deciding whether you should go for glazed or unglazed tile, we hope that this article will help clear things out for you. Since we have a lot of people coming to us asking us about the differences between ceramic tile and porcelain tile, we’ll also cover those aspects in the article. You can also read the respective articles on their topics by pressing the links that we included.

When you’re ready for it, we’ll also be more than happy to help connect you with the most relevant ceramic tile installers in your area to bid on your project, completely free of charge for you. In the end, if you don’t like their quotes or decide not to go with them after all, that’s completely up to you as there’s no obligation.

What is Glazed Porcelain and Ceramic Tile Flooring?

porcelain-tile

When you start looking around to purchase one or the other kinds of ceramic tile, it’s inevitable that you don’t either see them saying glazed or unglazed in relation to the product, and it’s important to know what it actually is so that you can make a more qualified purchase.

When you’re buying tile, you should know that they come in two forms, either with or without glaze on top of them. The bisque is the main part of the tile, on top of which the glaze is added. The glaze is basically a protective coating, which consists of liquid glass that is baked with the tile in the kiln, and during the process it sticks to the bisque. One of the reasons why this is added is because it will contain a range of decorative elements, and since the tile is inherently porous, the glaze adds a protective layer that not only protects against water but stains as well.

Colors

Various minerals such as silver, gold, copper, mercury, zinc and others are what add the colors in the glaze, and while you may have seen the beautiful material before, you might not have known that it’s in fact a liquid glass covering that was added. Iron oxides, chromium and more are used to make the finish you desire.

The vast range of colors that tiles are offered in is a direct consequence of the ability to glaze the tile. While you may love your tile’s look, if the glaze gets damaged in any way and it affects the integrity in the tile, you can’t simply repair it. That specific tile will need to be removed and a new one put in.

Glazing in itself doesn’t refer to a surface being glossy, which is what a lot of people think of when they hear the term, although it is often to give a high-gloss look. The term refers to the actual coating, the substance that is added. Net time someone uses it to make a description of the tile, you know that it isn’t correct since glazes can be matt also.

How much oxygen is available during the baking process that takes place in the kiln will also have a big effect on the color that the tiles turn out. Copper can either turn out turquoise or bright red depending on the conditions in the kiln.

The Temperature of the Kiln

Since you’re dealing with liquid glass that is being added on top of tile during the baking, you will want to make sure it has the right temperature during the process. Without sufficient heat it won’t properly fuse with the bisque, and too much heat could cause it to run off and end up in undesired places instead. The amount of oxygen inside the kiln can also affect the temperature that is needed.

Where Are Glazed Tiles Used?

There’s both a bunch of residential and commercial places where glazed tile is used. The most common residential purposes it has includes countertops, kitchen floors, backsplashes, bathrooms and decorative wall elements.

When safety is the biggest concern, which it can be in commercial places, unglazed may be preferred.

Benefits of Glazing

There’s a reason why people buy glazed tiles. You can see all the advantages below:

  • It allows for all the beautiful colors and designs that you can find.
  • Stain-resistance – covering the pores means that your tile won’t get stained if you drop something on it that would otherwise have stained it.
  • Fire-resistance – while it’s not the glaze as such that provides the fire-resistant features, these tiles are fire-resistant, which should be obvious from the fact they go into an oven that would otherwise have set them on fire.
  • Fade-resistance
  • Basically maintenance-free – while you owe it to your tile to wipe up spills, this option has barely any maintenance when compared to other flooring options.

Why You May Wish to Go For Unglazed Material Instead

The glazing of the material adds a range of beautiful colors to the material, but it also traditionally increases the cost when compared to the unglazed alternative. It’s also more slippery than the unglazed version.

While not a drawback of glazing, tile in general is not the cheapest flooring option you can go with, so if you’re on a strict budget there simply may be other materials that you might be prefer looking into before this one.

You should also know that if you crack the glaze sufficiently deep, you will see the underlying tile below which will have a different color, and it could leave a noticeable mark.

Unglazed tiles have their purpose too and are often used in commercial settings where a lot of traffic is expected. This includes everything from hotels to airports and everything in between. The only way these tiles won’t be matt is if they have been polished, which will create a highly-reflective surface as a consequence.

How is Ceramic and Porcelain Tile Made?

Once the clay and other elements have been formed in the desired shape, it’s left to dry and it is then put into a kiln which fires it at very high temperatures. The amount of time it is in the kiln as well as the temperature will affect the water absorption rate of the material, which is how it is determined whether what you have is ceramic or porcelain.

For it to be considered porcelain, the water absorption rate must be below 0.5%. What that effectively means is that when the tile is boiled and left in water after having been in the oven, it should add 0.5% or less of its own weight from the submersion into water. When the tile weighs more than 0.5% more after that process, it’s not considered porcelain, if you go by the definition used by most standard groups.

A lot of the benefits that porcelain has, it has because of its lower water absorption rate, and they’re the same as those that glazed ceramics would have.

Which Type of Ceramic Are You Buying?

Since porcelain is basically ceramic with a lower water absorption rate, we want to provide you with a warning. There are a lot of the materials out there that claim to be porcelain that aren’t. We know – it sucks but there’s nothing to do about it!

Porcelain isn’t a regulated title so your best option when it comes to going out and wanting to buy porcelain is to make sure you’re actually buying a tile that carries the¬†PTCA Certification Mark. It’s a voluntary certification but it will help ensure that the manufacturer has gone through rigorous testing of their tile in order to live up to the requirements they set forward, and that you will get the desired consequences from it too.

What You Need to Know About Grout

So the tile itself has now been well-protected with the coating, however there’s still the fact that between the different tiles is the grout which doesn’t have the same protection, is a porous material and is therefore exposed to the risk of mold and mildew. When installing ceramic or porcelain, this is the weakest link, why adding a sealant to the grout will also help make sure that it in fact doesn’t become a problem. Adding this sealant to the grout also helps make sure that it doesn’t get stained either.

green glazed tiles

How to Clean Glazed Porcelain Tile

The good news is that the material is extremely easy to clean and you will usually find that all it takes is the help of a damp mop. Otherwise, you may look for a mild cleaner for porcelain is what you will need. What that means is that it has to be non-acidic to avoid it harming the finish that was added.

Glazed vs Unglazed Porcelain & Ceramic Tile

For unglazed tiles, the same color of the tile goes all the way through the body of the tile, and while the glazed tile isn’t likely to show a lot of marks from wear, the unglazed one won’t show any. When you use unglazed tile, chances are you will need to apply a protective sealant in order to keep the material from getting stained.

If you’re not planning on reading anything else in this article, you should at least read the comparison below.

Type of tile Unglazed Glazed
How Thick is it? These are usually both thicker and more dense In comparison, these are traditionally not as thick
Slip-resistance The less-smooth surface provides better protection against falling Glazed tiles are easier to fall on
Danger of getting stained Since the pores aren’t coated, ceramic tile will absorb liquids that contain colorants The liquid glass added on top makes sure they don’t get stained even if you spill something.
What it looks like Earthy as a consequence of not having additional colors added to the clay. Whatever color or finish you may want.
How it’s made Nothing is added on top of the tile during the baking. A sealant may be added afterwards. The liquid glass coating gets fused with the bisque.

How to Tell if Tile is Glazed or Unglazed

As mentioned above, the only way that unglazed tile will be glossy is if it has been polished, and that’s an easy way to tell if it’s one or the other.

Their Performance

When the tile has been fired at higher temperatures and for longer, this tend to affect the color of the tile too, as well as its durability. Since some glazes require higher temperatures to properly fuse, that will also mean that you end up with stronger tile. As such, the general rule of thumb is that the darkness of the glaze is an indication of the durability of the tile, while it is not to say that lighter tiles aren’t durable, they might simply not be AS durable.

In addition, how matte the finish is will also affect the durability with the more matte ones being more durable also. Whatever project you’re looking to have the tiles installed for will require that you find the tiles that best serve their intended purposes. When you’re simply looking to have decorative tile installed, the requirements for their durability is significantly less than that of flooring tile.

When it comes to flooring tile, you will also need to consider their PEI rating. The PEI rating basically lets you know how durable the tile is and therefore what it can be used for, where grade 1 is only intended to be put on walls to look beautiful. Grade 2 can be used for bathrooms or kitchens, but it is still only one grade higher. When you start expecting a little bit more wear of the material, which will naturally happen when you have kids or pets, grade 3 is necessary.

This grading system goes all the way up to grade 6, which is the most durable.

If you’re ever wondering what an appropriate choice would be in your situation, you should reach out to pros and ask for their opinion too. They can give you advice on everything from glazing to PEI ratings and durability.

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