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-   -   Tile Industry Porcelain v. Other Porcelain (https://www.johnbridge.com/vbulletin/showthread.php?t=75872)

Ingeborg 07-29-2009 01:10 PM

Tile Industry Porcelain v. Other Porcelain
I just want to add to this since there seems to be a great bit of confusion about ceramic tiles versus porcelain out in the general public.

Porcelain is the "queen" of clay. It is a clay and the reason it is generally white is because porcelain has little if any impurities.

Ceramic is a general term applied to porcelain, earthenware, stoneware and even glass which is also considered a ceramic product. Pretty much since all of the above mention mediums are fired in a kiln, they are ceramic. Make sense?

Is porcelain stronger than regular clay tiles? Yes and no. High fire porcelain with a glaze can be pretty impervious to moisture and can be stronger since the glaze fuses to the clay. In other words, the clay and glaze become one. I seriously doubt that most production tiles are high fire. I say High fire which is somewhere in the range of 2400 to 25oo degrees farenheit.

High fire stoneware clay that is glazed and fired to around 2400 F is pretty low in absorbency but generally the glaze does not fuze to the clay body in the same sense that high fire porcelain does. I would have to go to my studio to check the exact amount of absorbency but it varies with the clay body and firing temperature.

In Spain and many european countries, there are tiles that have been in place for many years and most of them are earthenware which is a very low fired clay. Mexican tiles are low fired and they do ok outside as long as you don't have a lot of freezing and thawing. The problem with Mexican tiles is they can chip (due to the softness of the fired clay) if in heavy traffic area and are hard to maintain.

You're all probably yawning!

Ingeborg 07-29-2009 02:38 PM


I would like to add one point which I think is important.

Commercial tiles are generally rated on absorbency, hardness and coefficient of friction. Certainly, coefficient of friction is important. Just something to keep in mind when you make a choice. It's not fun to fall "$#$$ over tea kettles"

cx 07-29-2009 03:17 PM

I will readily admit knowing nothing at all about the clay industry that Ingeborg is familiar with, but let me clarify a bit from the ceramic tile industry side.

To be classified as Porcelain in our industry, a tile must be a ceramic tile, generally dust-pressed or extruded, which has a water absorption rate of 0.5% of its weight or less.

That's it. Excludes other impervious types, such as glass and metal, but if it's ceramic and has an absorption that low, it's porcelain. How you get it there is up to you as a manufacturer, but you generally gotta squeeze it harder and get it hotter, I'm told.

It can be glazed or unglazed, through-body colored or not, textured or not, look ugly or not, but if you make it outa clay and can get it dense enough to meet that absorption standard you can call it porcelain. :)

My opinion; worth price charged.

Ingeborg 07-29-2009 04:09 PM


I'm certainly no expert on the tile industry so I defer to you and your expertise. Isn't it a shame things can't be standardized to where the general public understands and feels comfortable in what they purchase?

I know that most, probably all industrial tiles are ram pressed. I find it peculiar that the tile industry regulates "porcelain" by purely the absorption rate regardless of the type of clay. I went on a ceramic cultural tour to China and went to the Porcelain capital of China....no where would you find an impure clay tile or pot called porcelain. They were the ones that invented porcelain thousands of years ago and of course they also invented tainted sheet rock:) But I am sparring with you...I love sparring with a guy in a top hat :) Marge are you watching!

I purchased Dahl tiles for my entire house and discussed in great detail with the distributor about how high they were fired, durability etc. They were not porcelain but stoneware...fine with me. Porcelain is cold compared to stoneware which has impurities in the clay to give it a lot more warmth and character. He assured me they were high fired and I asked fired to what cone 10 (2400 F)? Yes he said

I bought them and laid them and I love them but..I took a piece and fired it in my kiln and the sucker melted like molted lava. Not a high fire tile.

I will enclose a picture of these tiles another day just for your info.

cx 07-29-2009 06:40 PM

I split these posts from a thread inna shallow end to avoid confusion on that thread and give Ingeborg an opportunity to continue the discussion if she would like to do so.

Apparently don't everybody call porcelain porcelain the same as do we here inna tile industry, non? :)

Originally Posted by Ingeborg
I purchased Dahl tiles for my entire house and discussed in great detail with the distributor about how high they were fired, durability etc. They were not porcelain but stoneware...fine with me.

If those tiles came in boxes that indicated they met ANSI standards, Ingeborg, there would be no doubt what they were. But if they are not marked as meeting such standards, the only thing you can be sure of about the tiles in the box is that they are the tiles in the box.

My opinion; worth price charged.

Ingeborg 07-29-2009 07:15 PM


You are a charmer, yes the tiles are what they were, tiles in the box:) That's about it. They were not cheap but I hunted all over for them having seen them in the Pacific NW prior to our move to the SW and finally found them down here in Florida and I was elated. It meant that I wouldn't have to make them myself.

I installed them on my floors and they have been in place for about 9 years. (I still have to install some sort of baseboard tile since they didn't come with any trim tile) I love them but they are not slip proof as their specs stated and they are clearly not high fire stoneware tiles since they melted in my high fire kiln firing. The distributor assured me they were high fired stoneware, obviously he didn't know what that meant.

So what gives with the tile standards of the industry?

John Bridge 07-29-2009 07:45 PM

Have a look at this in the Liberry. It's a short account of tile making by my old friend Uri in the land of Oz. :)


ob1kanobee 07-29-2009 08:14 PM

This explains it all. Classifications, how they are made, all kinds of info...

Keep hitting the next button to go through all the pages............


Muddman 07-29-2009 11:19 PM

Well Ingeborg, as a fellow potter myself I too find it curious how things are classified for tile. And I always love it when someone says "its not ceramic, it's porcelain." :bang:

And I never thought to stick a tile in the kiln to test it out, I wanna see that pick. Makes me wanna through several different "porcelain" tiles in and see if they even make it to cone 6.:corn:

Ingeborg 07-30-2009 07:20 AM

Hi Gregg and fellow potter,

Some time when you have extra space in you kiln throw one of them "porcelain" or are they ceramic :) tiles in and see if they melt. I would be curious to know at what cone. My guess is they are fired below cone 6. Just a guess. I will have to read the info from John B. friend from OZ. Maybe he mentions the temp they fire tiles. I skimmed the report but will need to take the time to read it in detail this p.m.

I think I laid the Dahl tiles in 2000 and that was before I had a digital camera. I threw the molten tile out in one of my cleaning fits at the studio but for giggles I will fire one the next time I fire a bisque (to ^05) and then another tile when I fire the dragon to ^10 Reduction. I will send a picture of the results.

If you do the test, don't forget to fire the tile on a dish with a lip or in a bowl just incase it will melt which I am going to bet it will. Don't want a ruined kiln shelf.

John Bridge 07-30-2009 07:47 AM

Uri didn't specify at which temp. vitrification takes place, but he raises the bar for porcelain tiles. While the tile industry declares that anything with an absorption rate of .5 or less passes for "porcelain," Uri sets the rate at .1. :)

The standards we speak of are directed toward lay people. The language is not terribly technical for a reason. Tile setters, for example, do not need to know how to make tiles; they need to know how to install them. It is, however, nice to know that the tiles you're installing will hold up.

Sales people need a certain amount of information as well. For example, they might not know at what temp. a tile was fired, but they will know its break strength. That info is in a little book kept under the counter. Sales folks and installation folks will also know the PEI rating of a glazed tile, while they might not know exactly how that particular tile did in MOHS testing.

Co-efficient for friction is something we are becoming more and more concerned with. The standard for that is being developed, and an attempt is being made to make it international.

The standards, which are voluntary, by the way, are used as a guide, and they are minimum standards. They are meant to comprise a threshold of knowledge that most people throughout the industry can easily understand. They certainly don't hold anyone back from delving deeper into the science of the industry. :)

ih8caulk 08-04-2009 05:27 PM

Losing my hair looking at tiles I was intrigued by something today...........

Guy at the Dal Tile store saw me looking at all porcelain tiles. He asked what I was doing, up to, etc. and I told him I was looking at tile for a shower. (Had some samples in my hand & told him what color range I was looking in).

He asked me why I wasn't looking at the ceramics and I told him because I was told ceramics are a no-no. He went on to explain to me how their ceramics are as tough as their porcelain due to high fire, etc. etc.

Now, I'm reeeeeeeally confused. Why do they even separate their tile displays into porcelain & ceramic then???

I think I've found a couple of really nice looking tiles (and looks like they're color-thru too). Price is a little lower too, but is what he's saying true???


cx 08-04-2009 05:41 PM

Welcome, ih8caulk. Would you please go to the UserCP above, find Edit Signature and enter a first name for us to use. :)

Originally Posted by Ih8
He went on to explain to me how their ceramics are as tough as their porcelain due to high fire, etc. etc.

His porcelain tiles are ceramic, as we're discussing above.

Whether they are all "as tough" as one another may be an entirely personal judgement on his part. There is no industry standard by which to compare toughness.

What you can do is look for the label on the box that says the tiles meet the testing requirements for whatever classification is claimed on the labeling.

If there is no such labeling, you can believe what the salesman is telling you, or not. But you'll really have nothing against which to compare his claims.

My opinion; worth price charged.

Ingeborg 08-04-2009 05:57 PM

If the color is thru and thru it would most likely be porcelain, a type of ceramic product. It doesb't make it any better or any worse it's just what it is.

Personally I would pick the type of tile that I really like and one that fits my budget. Ask them if it will work in your particular installation/use and make sure you install it according to specs. In other words, if the tile is recommended for floors only then don't put it on the walls, ask all of the pertinent information and then go for it.

I don't know if that helps. I hope so.

ih8caulk 08-04-2009 06:30 PM

Being more specific he said that their ceramic are fired hot.

Also that their ceramic is 250psi tested. (Dunno what their porcelain is)

Also found this on their website......

"•Manufactured in accordance with ANSI A137.1 standards" And their warranty doesn't seem to make any distinction between any of their tile families.

Also, when another gal there said she had been listening to my question and was wondering the same (liked a ceramic they had but wanted it in porcelain) another sales guy reiterated the same stuff and said that it's mostly because *THEIR* ceramic is mfg'd w/ exceptionally high standards compared to more "breakable" chinese ceramics found at the big box stores.

My personal concerns would be two-fold:

#1.) That it's no more susceptible to cracks/breakage than porcelain

#2.) That there's virtually no difference in how tough it is to keep clean vs porcelain.

(And before anybody barks.....yes....I realize porcelain tile is basically a *kind* of ceramic tile. Us layfolk just seek more english & less jargon) :deal:

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