Wednesday, 8 July 2015

The Technicalities of Ceramic Tiles (And their variants)

We are at the epicenter of the largest tile production area in India. In fact, we are the Epicenter. Most of the tiles sold in India are largely manufactured and supplied from Morbi. However, BA has found many traders, retailers, sale persons and (surprisingly!) manufacturers who are not always very much aware of the variety of tiles and their differences.

We have therefore decided to highlight the Ceramic Tiles and their variants in a long brief article. Surprised? How contradicting? An Oxymoron so to say. LONG BRIEF. We know it is puzzling to some and largely funny to most but yes this series will have articles with LONG BREIFS, because, we may have to write a hand book to cover everything if we go into the details, so whatever we will summarize here will be very brief. But as Ceramic tiles sector has many variants, the article or the series thereof will be quiet long spanning a number of issues.

To give you an overview of the total series, we will be covering:

1.    Ceramic Wall tiles
2.    Ceramic Floor tiles
3.    Polished Porcelain tiles
4.    Soluble Salts Technology
5.    Multi Pipe Technology
6.    Salt and Pepper Technology
7.    Double charge.

With the preceding list, you will probably agree to our linguistic adaptation of LONG BRIEF presentation.

Tiles Basics

Ceramic tile is a complex subject. Let's cut down the complexity and make it simple. There are two major types of tiles, quarry tile: that is a tile that is made by extrusion from natural clay or shale and a tile that is made by the pressed dust method. The pressed category includes wall tiles, mosaic tiles, and floor tiles. All types of tiles can be glazed or fired as unglazed. Glaze is a ceramic surfacing material that is used to provide a certain appearance. Let me restate this point: any ceramic tile type may be glazed or unglazed. This includes porcelain tiles.
It may be intriguing to some that how can dust be so strong. When wet dust is pressed under high pressure, it retains some moisture which helps the body stay together. As all particles are extremely small and uniform, they compact into a strong body. The moisture in the tile after pressing is 5%. The tile is then dried and will still retain moisture of about 2%. Once it is baked in the oven or kiln, its moisture evaporates and forms a strong body. If the glazing is desired, it should be applied after drying.
Mostly these tiles are differentiated on the basis of their water absorption property. Water absorption of tile is decided by the selection of raw material used for the body of the tiles and the manufacturing process employed to produce it. In today’s world a number of technologies are available for manufacture of tiles and hence there are a number of types of tiles available.
It must be noted that it is the body that absorbs the water and not the glazed surface. This water absorption determines the classification of tile.


A Wall tile has about 7-20% water absorption. That may be news to some, but it is merely a fact for the technical experts. This is also the reason why it cannot be used at a number of places.  The water goes into the body when it rains, dews, from pools and fountains, and even atmospheric condensation. All these lead to the tile becoming heavy and may even crack due to temperature variations and the water effect in these variations.
Wall tile is made for a purpose, sticking on a wall, although in India, people have found alternative uses for the same, including on floors, where the foot traffic is very low. A wall tile should be beautiful as it is largely used for Decorative purposes. Moreover the size must be close to uniform as there is usually a small space between each tile (called a grout joint). The relatively soft body of wall tile makes it easy to cut to fit (including round holes for plumbing fixtures) and helps the tile to stick to the wall without sliding.
It is normally argued by laymen that GLAZING is water proof and hence the tiles are safer even in water logged areas. Yes it is true that glazing is water proof, but water seeps into the tiles body through GROUTS at the JOINTS. It is worth noting that the water absorption is in the body and not the glaze. With advancement of technology, high quality water proofing material can be used to protect the body of the tiles.


Ceramic Floor tiles as the name says are manufactured for flooring. The first generation of Ceramic floor tiles has lower water absorption. This is largely due to better compaction and very low porosity. Normally porosity and water absorption are directly related. Lower the porosity, lower the water absorption. The water absorption of ceramic floor tiles is 5-6%.
As these tiles are more compact, they tend to be heavier than wall tiles. So, they cannot be used on walls. Because of low porosity, the cement and mortar cannot bind with the body of the tile. It is easy to stick the wall tiles which have higher porosity, on walls, but not these floor tiles.
They can be glazed and in the Indian context they are actually glazed. This enables the tiles to be more beautiful and extremely aesthetic. The glazing also prevents water absorption. However, at the joints, water proofing needs to be done.
The flexibility of Ceramic tiles is that it can be cut at the site while laying on the floors.
It is recommended that these tiles be used indoors and not outdoors as they cannot resist consistent downpour of water or tremendous foot traffic. They are for medium range traffic. In high traffic areas, the glazing will give away, making them futile.
Polished Porcelain Tiles
This is one of the best inventions of modern day ceramics. These tiles have very low water absorption- as low as less than 0.5% which is just miraculous. These tiles are highly compact and dense. They are very much like natural stone and can be polished similarly. Polishing gives a very good shine to the surface of these tiles. Moreover, as it is like stone, on further polishing, the tile does not lose its color. Through the thickness, it has the same color and grain structure.
They can be used in high traffic areas as well. Homes, Dining rooms, drawing rooms, living rooms, bed rooms etc. all can be floored with polished porcelain tiles.
They have very high scratch resistance. They are also very good abrasion resistors. Hence they can be used in commercial spaces like malls, shopping complexes, airports etc.
Does this mean that porcelain tiles are the best for all purposes? No. To further elaborate let us take a look at some of their drawbacks.
Having virtually no water absorption, they are not recommended for walls. However, if you wish to use them on walls, the adhesives have to be very good and a good supporting element in needed in the structure.
Its advantage is, it can be cut like stone, but you need a special cutting agent of high cost to cut it and shape it to your purpose of application.
There are little holes on the surface. These do not absorb and take water downwards in the tile body, but are not stain resistant. (Though technological breakthroughs have been made to reduce staining in these tiles.)
These tiles also suffer from limited color availability. They are found mostly in natural colors and stone type looks.
Most of these are quite costly compared to the previous two that we have assessed.
Polished Porcelain Tiles can further be divided into four categories on the basis of the manufacturing technology used. These divisions are done to achieve better designs.

[A]: Soluble Salts Technology

As already mentioned, one of the many limitations of polished porcelain tiles is the limited color availability. SST employs a method to fight this challenge to a certain extent.
In SST, the soluble salts are dissolved in water. The green tiles are then sprayed with this water. This forces the water to penetrate within the depths of the tiles. The printing is done with different mesh size for getting the required designs. The tiles then pass through three water sprays. This makes the salt penetrate to 2-3mm in the surface. On firing, the water evaporates and the salt remains in the tile, giving it a design. This design is visible after polishing the tile to about 1-1.5mm.
One major limitation of this technology is that the availability of colors available is limited to Brown, Yellow, Grey and Green. So, if we want a replacement of Red Elegante the red king of Italian marble, SST would fall short.

[B] An innovation of SST: Multiple Pipe Technology

To overcome the limitation of SST, multi pipe technology was invented. It uses 3 to 4 color powders to impart print. The powders are applied before pressing, through the powder feeder. White and Ivory are directly fed on the feeder grill. This mixture of powders is taken to the cavity of press to feed the powder and then pressing is done on the tile. So these powders penetrate the tile, forming delightful designs.
Using Multiple Pipe tiles is a practical solution. Technically, however, the powders used in this process are quite costly, making the technology commercially unviable in many countries. Moreover, homogenous colors were not found in the produced tiles, which again put off buyers who wanted a large stock.

(C) Salt & Pepper Tiles

This is another innovative technology, developed to offset the color print and design limitation of the polished porcelain tiles.

Here, the main body powder, which is Ivory and white, is mixed with other colored powders, by use of screen vibrators. These powders are chosen based on the required color of the tile. The tiles are then pressed. The colors are already mixed with the body, so they form a homogenous mix within the pressed green tile.

Once these pressed tiles are fired, we get unique black spots on the tile, as if a lot of salt has been sprayed with a tinge of pepper. This is why they are known as Salt and Pepper tiles.

The reverse can be done by having Black as the base powder for the body and white being used sparsely at about 3-4%. This makes the tile totally black with white spots.

Instead of Black, orange or other colors can also be used, thereby giving a granular output.
These tiles are used in homes as well as commercial buildings. However, they still have some color and design limitations.

D] Double Charge technology: The Presently accepted solution.

The very popular technology that has replaced both the above technologies is the DOUBLE CHARGE TECHNOLOGY or the DOUBLE LOADING TECHNOLOGY.
In this technique 70% of the thickness is manufactured using low cost base powder and clay. The 30% of the surface side of the tile contains base powder and three different color powders.
Double charge or double load means, the cavity is loaded twice. First, only base powder that is employed for 70% of the tile; then the other base powder and three other color powders that form the surface. When these powders drop on grill of the feeder, a uniform pattern is formed as all the three powders have different density.
Depending on the feeder grill, different types of designs are formed on the surface of the tiles. Both these different charges are pressed to make a tile.
To achieve a balanced combination of Surface patterns, Hardness and Stain resistance, double charged tiles are upgraded from 1st generation to 3rd Generation. In the third generation, micronized powder is fed inside the tiles, requiring more pigments and stains, eventually increasing the cost. However, the final result is three dimensional, a perfect replacement for natural stones.
In double loading, the surface with the patter has a very low porosity giving it a more glossy shine and very less water absorption, compared to SST. The Low porosity enables it to be highly stain resistant.

Commercial Success

It seems that Double Charge or Double Loaded technology has proven to be a commercially viable option. The manner in which many manufacturers are already manufacturing these tiles and many more are planning to move ahead with the same certainly portrays a very bright future for this technology.
However, as the production time and double pressing process add to the costs, there will always be a big question mark over its long-term sustainability as a solution. It is believed that till nothing else is there to beat double charge technology given its cost/value proposition; the technology is here to stay. It seems the TINA (There is no alternative) factor seems to be working in its favour right now!
As we mentioned at the start of the article that humans are always thirsty for things better and innovative, we are sure, next year in the same period, we may have something else challenging the Double Loaded technology.
But for now, it is widely accepted as a great solution for tile manufacturers.


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