Glaze Ceramic, Glazed & Polished Porcelain… what does it all mean?

Firstly, it’s important to understand that technically all tiles are CERAMIC tiles. The terms Glazed Ceramic, Glazed Porcelain, Technical Porcelain, etc., are used in the industry and retail world to differentiate different types of Ceramic tiles.

So, what makes one Ceramic tile different from another? Let’s Talk Cake!

Picture an everyday sponge cake. In general the ingredients for a sponge cake are flour, caster sugar and eggs – pretty simple. So, the idea is to mix the correct quantity of ingredients, put it in a tin and cook it at the right temperature for the right amount of time to cook the ingredients, remove the majority of the water content and make the cake rise. Congratulations, you are now a master chef! Now, let’s say we want a cake that is not as moist, but of a denser consistency. We might add ingredients like baking soda, more eggs and butter, and cook it for longer at a higher temperature to remove more water. In essence, the basic ingredients indicate it’s still a sponge cake, but because of the added ingredients and the cooking process, we now have a different type of sponge cake – the same applies to Ceramic tiles.

The combination of clays, the addition of silicas and minerals, the pressing or moulding of the ingredients and the time and temperature it’s fired at, gives us different types of Ceramic tiles.

The one important thing that both the cake and Ceramic tile share in common is water content. The more water in the cake, the more moist and soft it is. Of course the opposite applies – being the less water, the more dense the cake is. With Ceramic tiles the same applies, and it’s this level of water content (or ability to absorb water) that gives us varying types of Ceramic tile.

 

Tile water absorption diagram

Figure 1: Length of cooking time and degree of temperature effect on water absorption of tiles

The diagram above shows the basic difference between a Glazed Ceramic tile and a Porcelain tile. A Glazed Ceramic tile will have a higher water absorption rate (3%-6%), and therefore is a softer product, whereas a Porcelain tile must have less than 1% to be classed a true Porcelain tile, and therefore is a harder and denser product.

Tip: A good way of explaining water absorption to a customer is this:

If you put a Ceramic glazed tile and a Porcelain tile in a bucket of water, the Ceramic glaze tile will weigh 3-6% more than its original dry weight, and the Porcelain tile will weigh less than 1% more.

Why is water absorption an issue?

Good question, glad you brought that up. There are a couple of basic reasons why water absorption is important. Firstly, the more water a tile is able to absorb the greater the likelihood the tile will expand. Don’t forget, tiles are made of clay (dirt from the ground) and clay will expand and contract depending on the content of water. If a tile expands too much in a tiling system they could crack, pop up, etc. Now, before we all panic, 3-6% water absorption is very minimal and it is rare that damage will happen to a tiling system if the system follows Australian Standards. This calls for correct glues to be used, expansion joints added and grout widths adhered to. Builders today are very good at ensuring these systems are followed. So, simply if a tile has the potential to absorb less water, the less likely the tile will expand and contract.

Secondly, and probably the most important reason for water absorption, is that the water content of a tile determines what finish a tile can have on its surface. A basic Ceramic tile is a soft biscuit in comparison to a Porcelain tile and so can only have a glaze applied to its surface. A Porcelain tile however, with its dense and stronger biscuit body, can also be glazed as a basic Ceramic, but more commonly it can be mechanically treated with diamond cutters to give a matt, honed, semi polish or full polish surface. These are referred to as Technical Porcelain.

Let’s talk Glazed Ceramic Tile

Your basic Glazed Ceramic tiles are also known by many names, some common variations are Monocottura, Monoporosa or Bicottura. They are single (mono) or double (bio) fired tiles, and generally at around 1000 degrees Celsius. Because of their softer ‘structural body’ (also referred to as biscuit), a protective layer of engobe and glaze is applied to the tile surface. Engobe stops any water absorbed travelling in the body of the biscuit to the top surface layer, while glaze gives the tile its strong surface wearing properties and is what stops water and dirt absorbing into the tile surface and causing a stain. Glaze comes in unlimited options, which is why you find basic ceramic tiles in thousands of textures, colours and gloss levels. It’s important to note, Glazed Ceramic tiles have been around for thousands of years and have stood the test of time, and for all intents and purposes they are a hard wearing and economical covering – and still today your basic ceramic tile is what makes up the majority of tile used in residential housing throughout the world.

Layers of a tile

Figure 2: Layers of a tile

Photo of tile layers

Figure 3. Top: Glaze; Underneath: Engobe Layer – Tile Body, not visible but referred to as under glaze biscuit

Tip: Light coloured tiles generally show less effect from general wear and tear than dark glazed tiles, so try to avoid blacks or reds, especially gloss, in high traffic floor areas.

Rounded Edges

Rounded edges on a tile

From a construction process, Glazed Ceramic tiles are the most economical tiles to lay, as the softer biscuit tends to cut quite easily with manual tile cutters and basic tools, and sizes are commonly on the smaller side (up to 400x400mm), therefore alleviating the need to straighten walls or level floors as the glues tend to capture these variations.

Another cost saving aspect to laying is that Glazed Ceramic tiles tend to have rounded edges. This helps the tiler get the levels between tiles as close as possible without having to be 100% perfect. The rounded edges are softer underfoot and combined with the grout lines, gives the tiler a bit of play and grace when laying tiles.

 

 

Rounded tile diagram

Figure 5: Rounded tile surface

So what is a Porcelain tile?

Like Glazed Ceramic, Porcelain tiles have also been in existence for many years, but in the past have predominantly been used in commercial applications as the resources and technology needed to produce this product has meant that it was expensive for most volume residential building applications.

However in the last decade there has been an increased availability of this product in both glazed (like Glazed Ceramic) and technical finishes (like Polished Porcelain), as improvements in technology and process methods have meant that production costs have reduced to economical levels and the quality and factory output is much more consistent.

Quality and output is much more consistent…what does this mean?

Let’s go back to the cake for a second. Let’s say we are having a cake stall and want to make 10 cakes to sell. We can assume that by adding the same ingredient quantities to 10 tins and cooking the cakes all together at the same temperature and length of time that we will get 10 identical cakes, right? Well, sometimes we do and sometimes we don’t. Why? It could be the combination and mix of ingredients, or the positioning of the cake in the oven. There are lots of things that can go wrong and we may end up with some dodgy cakes that we might not be able to sell, or sell at a discounted price. The same applies to Ceramic tiles. The basic set up to make Ceramic tiles means that if we make 10 tiles we may end up with six that are first quality and four that are dodgy and might be classed as seconds. With improved and smarter processes and technology, we can now produce a better product (porcelain), with higher first quality yield rates at an economical price. So when we make 10 tiles we get nine good, and that’s more tiles to sell!

So, Porcelain tiles are effectively ceramic tiles of a denser, stronger nature. Using a combination of varying clays, silicas and additives, extruded under extreme pressures and then fired at high temperatures, we get a ceramic tile that is much superior to a monocottura product. It has minimal water content and absorption properties and therefore can not only have glaze added to its surface, but its surface can be mechanically treated to give us a honed, matt, semi polished or high polished surface.

Technical Porcelain - the surface is mechanically treated

Figure 6: Technical Porcelain- the surface is mechanically treated. Pictured: Polished, External, Matt.

Porcelain - This has a through body biscuit meaning the colour is similar to the surface glaze

Figure 7: Porcelain – This has a through body biscuit meaning the colour is similar to the surface glaze

What are the main characteristics of a Porcelain Tile?

Glazed Porcelain and Through Body Glazed Porcelain

As Porcelain can be glazed, you will find that the entry level Glazed Porcelain will be similar in visual finish to a Glazed Ceramic tile (as per Figure 4) and in most cases it will be visually impossible to detect the differences between the two. In actual fact, they both perform exactly the same (as in cutting, laying, etc.) and the biscuit of the tile tends to be a generic colour. Technically though, Glazed Porcelain has a stronger and denser biscuit.

The more advanced Glazed Porcelain tends to have a thicker biscuit, and the colour or texture of the biscuit is similar to the surface glaze (see Figure 7). This is so if the surface of the tile was to be chipped it would blend in with the biscuit (see Figure 8).

Porcelain Glazes

Figure 8: Porcelain Glazes

Technical Double Loaded and Technical Through Body Porcelain

Technical Double Loaded and Technical Through Body Porcelain are the two most common forms of Technical Porcelain. Remember the term ‘technical’ is used to highlight that the surface is not glazed and is mechanically treated.

Double loaded is simply an economical way of producing Technical Porcelain by applying two layers of Porcelain together – the top being the decorative colour. This top layer can then be mechanically treated, however if the tile is chipped or damaged beyond the top layer, you will see the bottom colour of the biscuit come through. For all intents and purposes, Double Loaded Porcelain is extremely strong and the most common form of Technical Porcelain in the market (see Figure 9).

Figure 9

Figure 9

Through Body Technical Porcelain is where there is only one layer and the tile is the same from the top through to the bottom. The top surface is then mechanically treated as required. It is commonly used in European porcelain production and is quite expensive to make and buy (see Figure 10).

Figure 10

Figure 10

PEI Rating

As Porcelain can also be glazed, the same PEI ratings apply to this surface as per Glazed Ceramic tiles. The PEI, or Abrasion Rating, relates to the degree of friction a floor or wall tile surface will withstand before the glaze performance is affected, and has nothing to do with the strength of a biscuit.

With regards to Technical Porcelain (that is, Porcelain which has been mechanically treated to produce a matt, honed, semi polish or full polished surface), these tiles do not fall under PEI ratings as there is no glaze to its surface.

Rectified Edges

More technically advanced Glazed Porcelain, and in particular Technical Porcelains, commonly come with ‘rectified edges’. Unlike Glazed Ceramic and entry level Glazed Porcelain tiles that have rounded edges for ease of getting levels right between tiles when laying, rectified edges are sharp with micro bevels and are a by-product of the Technical Porcelain being cut to size after production, rather than the cookie cutter production methods entry level glaze products go through. Being rectified edges, tilers must take extreme care to get the level between tiles correct, otherwise ‘tile lipping’ occurs and this can be felt underfoot. It is also where dirt tends to get caught, is visible in natural lighting conditions and can make a $100/m2 tile look like a $10/m2 tile if laid poorly (see Figures 11 & 12).

Rectified Edges with Micro Bevel

Figure 11: Rectified Edges with Micro Bevel

Figure 12

Figure 12

General things to know about tiles

Laying Brick Bond

Oblong shape tiles, like 300 x 600mm, 400 x 800mm or even 600 x 1200mm are generally made by cutting down larger tiles. This is more so with Technical Porcelain. When tiles are made it is a natural characteristic for the tile to have some curvature or bow, that is where the centre of the tile is raised (see Figure 13).

Figure 13

Figure 13

Because of this, when a tile is laid in a brick bond fashion, the middle of the tile does not line up with the ends of the other tiles. This unevenness is referred to as ‘lipping’ and can be felt underfoot or seen in natural light (see diagram 14).

Tile lipping

Figure 14: Tile lipping

To avoid this lipping, we advise people not to tile in a brick bond fashion without checking that the curvature of the tile is minimal, and therefore avoiding the variation. If however there is some curvature and the client wishes to have a brick bond effect, we recommended that tiles are staggered only 200mm off the tile edge, rather than half (as per normal brick bond finish). By doing this, you can hide the curvature to a degree and still have that staggered look (see Figure 15).

Brick bond tile layouts

Figure 15: Brick bond tile layouts

Batch/Shade Variations

An inherent property of tiles is batch or shade variation. Again, going back to our cakes, you are never going to get identical looking cakes out of one cooking period. The mix of clays and firing process in tile production means that within one run we could end up with multiple batches or shades. Luckily we have moved on from visual inspection of tiles to determine shade consistency. Advanced technology is able to sort out one from another pretty easily and our stock control systems mean that we will only send out one batch or shade per house lot, so there is no need to stress.  When we receive a shipment, we check what we has come in to a ‘master tile’. If the variation is too great we ensure we re-sample the tile to all our customers, so you will always be up to date with the latest.

One important thing that you must always tell your clients is:

Batching and shade variations are inevitable in all tile products and the tile you have chosen is indicative only to what you may receive. There may be no issue, or it may vary slightly, however it will still go well with your selection. Our supplier is very good at keeping us up to date with the latest samples, and if there is an extreme change we will be informed and in turn will inform you.

Learn it, live it, breathe it.

In saying this, some tiles are ‘designed’ with batch or shade variation to enhance the natural characteristics the tile is supposed to represent. There is a rating chart that governs this design variation (see Figure 16). The majority of Hynes tiles follow V1 and V2. If we offer a tile with a V3 or V4 rating we will advise you of this so as to explain this to the client.

Tile variation ratings

Figure 16: Tile variation ratings

Trims and Angles

There are so many trims and angles available on the market to decorate and finish off tiles. The most commonly used are floor angles to finish off the edge of a tile where they meet a different substrate (like timber flooring), or square or round trims on wall tiles to hide the top edge of a wall tile (see Figure 17).

Grout Lines

Grout in an inevitable part of the tiling system. It’s important that Australian Fixing Standards are adhered to, especially in the grout and expansion line process. Apart from being there to accommodate expansion of higher water-absorption tiles, therefore being the first thing to fail if expansion occurs, grout lines serve another purpose. With any ‘pressed’ production tiles (commonly Glazed Ceramic and entry level Glazed Porcelain), the grout lines need to be a minimum of 3mm. The reason for this is that as a pressed tile, the size of one tile to another, even in the same box, can vary minutely. Why I hear you ask? Well, let’s go back to baking again. You can compare a ‘pressed’ tile to a cookie being cut by a cookie cutter. Essentially they should be the same, but with the firing process one may grow slightly bigger than another, and as these tiles are not rectified (cut after production to a standard size), but have rounded edges, we need to accommodate for this size variation in the grout lines (see Figure 18).

Grout Lines

Figure 18: Grout Lines

So as you may expect, with a lower water absorption tile that has been rectified (cut to an exact size after production), you can get a closer grout line, commonly 1.5mm. However, you should check with your building and construction department before offering this grout line spacing with Rectified tiles, and under no circumstances can you offer a tiling system without any grout line. That’s Never with a capital N!

Slip Resistance

Slip Resistance can be very technical, but in simple terms, you must choose a tile that is suitable for the area it is to be used in and in most cases it’s very logical. Slip Resistance comes into play when we are talking about tiles for balconies, patios, alfresco areas and even in shower bases. With regards to tiles in shower bases, although there is no governance on this with residential applications, we strongly advise not to use a high gloss Glazed Ceramic or Glazed Porcelain, or Technical tiles with a honed, semi or full polished surface.

With regards to external areas, tiles must meet minimum Slip Rating requirements. To date, the common method of testing a tile’s slip performance has been the ‘ramp’ test. This test basically is where a person is strapped to a harness, wears some rubber shoes and the tiled floor is wet and tilted to an angle. When the person slips, the rating is measured.

Under no circumstances should an internal tile be used in an external floor application.

Tip: Always be sure to tell your clients that Slip Resistant tiles are harder to clean than non-slip internal tiles. Ideally, use a hard bristle brush to scrub off dirt and then mop away with clean water, or hose off if outside. 

Slip Rating System

R9 Person slips at a 3 to 10 degree angle of elevation
R10 Person slips at a 10 to 19 degree angle of elevation
R11 Person slips at a 19 to 27 degree angle of elevation
R12 Person slips at a 27 to 35 degree angle of elevation
R13 Person slips at upwards of 35 degree angle of elevation

The most common tiles available on the market for residential applications are R10 and R11. Hynes has a variety of tiles to cater to these applications.

Tile Direction

Pretty much all tiles come with some form of directional laying instruction. This is commonly referred to as the ‘arrow’ on the back of the tile. Your tilers should be aware of this when laying, but it’s good to know when showing a client that the tile was designed to go in a particular direction (see Figure 19).

Figure 19: Tile direction

Figure 19: Tile direction

Optical Haze

With more and more Polished Porcelain being used in residential homes, it’s important to understand and convey the characteristics and performance of this product to client. High gloss polished tiles tend to be compared to ‘mirror finish’, however clay is not mirror and the nature of clay varies due to the characteristics of the material. Light reflected in a mirror is called ‘specular reflection’ and is why you can see your reflection clearly, whereas light reflected from a polished tile surface is called ‘diffused reflection’, and this diffusion can be caused by the molecular structure of the clays, the polishing process, or a myriad of other reasons in the production process of tile. Various colours will show it more than others and it can vary from batch to batch of the same tile. It is also more obvious in certain light conditions. Manufacturers around the world are constantly looking at ways of improving the aesthetics of Polished Porcelain, but in the meantime, optical haze exists in some degree in all Polished Porcelain and we need to show a duty of care to our customers by letting them know that this is inherent in this product (see Figure 20).

Polished tile optical haze

Figure 20: Optical haze

Tip: Optical haze is more noticeable in natural light, with skimming across the surface (as per the picture). Avoid using Polished Porcelains where there is a lot of natural light via floor to ceiling windows. For example, from the entry door through to the back living room. Bathrooms, kitchen splash backs, and laundry areas where minimal natural light occurs are ok.

Client tile FAQ

Should we seal grout?

One of the biggest issues with tiles is grout – it’s the necessary evil.  Grout is basically discoloured cement. It is very porous, however some grouts have additives to increase flexibility and reduce porosity. Sealing of grout can help, but it’s important to remember that sealing grout is a maintenance regime and should be constantly done. To help keep grout clean, dirt and dust should be vacuumed before mopping, as it is normally dirty mop water that makes the grout dirty. Avoid soapy detergents you can buy from supermarkets and use phosphoric cleaners instead. Clean mop water regularly during the cleaning process – do not use one bucket of water for the whole house as you will only be putting dirty water onto your grout. There are grouts called Epoxy grouts. Visually they look like silicone and tend to be used in commercial places like kitchens or McDonalds. These grouts are expensive and a specialist is needed to install.

What tiles need sealing?

Glazed tiles, whether Ceramic or Porcelain, do not require sealing. The glaze acts as a decorative and protective wear coating and nothing – no dirt, grime or stain – can penetrate this, unless the glaze is damaged. Most Technical Porcelain, being mechanically treated, tends to have a protective sealer applied to the surface (being either NANO or Sealer Glaze). Tiny pores open up when Technical Porcelain is machined. These pores need to be filled to avoid dirt, grime or stains penetrating into the surface.

How long will the sealer last?

There is no definitive timing on this. Resealing tiles is no different to repolishing timber floors; however it is easier to see when the polish on timber floors has worn off. It depends on the traffic and maintenance, but a simple test is that if you drop water onto the tile and it beads like that of water on a waxed car, then the sealer is still present. If the water spreads out flat, then the sealer has probably worn away from the surface and may need attention.

If I drop something is it going to crack or chip my tile?

Today most tiles are laid on concrete slabs with a flexible adhesive. If the tile is laid with the correct bed of glue (as in with a notched trowel and not ‘dabbed’ on – a cause of drummy tiles), the tile will adhere to the substrate effectively and in most instances the tile will not crack. In fact, if a bottle was dropped onto a correctly adhered tile the bottle should smash before the tile cracks. In older homes built on timber stumps and where the substrate was made of cement sheet applied to timber or yellow tongue boards, there was a lot of movement and flex – therefore if the same bottle was dropped, the tile would probably crack before the bottle.

What warranty period do I get with my tiles?

The Hynes Group is one of Victoria’s leading importers and distributors of tiles. It prides itself on developing products to meet and exceed market expectations. We work closely with our manufacturers to ensure our products are tested for quality, performance, durability and conformity to Australian Standards.

Under normal wear conditions and the suitability of product to the area it is used, the Hynes Group guarantees that tile for 10 years.

I have heard there are quality issues with Asian made tiles, is this true?

This is a common question and somewhat justified. Twenty years ago the Australian tile industry imported tiles mainly from Europe, but as the Asian region became more industrialised, the Europeans who developed the kilns and presses to make tiles started selling this technology to the Asian region. The initial volumes were for the domestic market, but as the Asians became comfortable in production they started copying what the Europeans were doing.  The first lot of tiles coming into Australia from Asia were quite poor, however over time, with improved technology and tighter development controls, the products now coming out of Asia are equivalent to European standards of the equivalent product. Sure, the Italians and Spanish were not all that stupid in selling the Asians all their trade secrets, so the best stuff still comes out of Europe, but for what is used in everyday residential homes, the Asian products are fantastic and the Hynes Group guarantees it.

Is Porcelain better than Ceramic?

In essence, yes. Porcelain tiles are better than Ceramic in terms of strength, quality and finish options available, however ‘all’ tiles have a place in any construction process. Choosing a tile is a matter of specifications required, the look you want to achieve and ultimately budget. Overall, ‘tiles’ are the most durable, environmentally sustainable and healthy flooring option for your home. Whatever tile you choose, you will be investing in the long-term value of your home.

My son has asthma, is this flooring option good for him?

One of the great benefits of tiles is that these floors do not harbour dust mites or other nasties and are allergen free.