Porcelain
or Ceramic Tile?
What's the difference?
In my many years of installing
and selling tile, I am continually asked about the difference
between porcelain and ceramic tile.
After some extensive research, I have found that there only two organizations
that have attempted to define standards to rate tile. One is The American National
Standards Institute (ANSI) and the other one is The Porcelain
Enamel Institute (PEI).
I was surprised to find
out that these organizations do not recognize the terms "porcelain" or "ceramic" when
referring to tile. It seems that manufacturers and salespeople
have promoted these terms themselves to guide customers on
their purchases of tile.
Tile is rated on it's ability to withstand water penetration and it's resistance
to abrasion.....period!
A definition used by these
organizations is:
*Tile
is a surfacing unit that is made from clay or a mixture of
clay and other ceramic materials, called the body of the
tile ( the bisque ), having either a glazed face fired to
a temperature to sufficiently produce specific hardness,
density, or physical characteristics.
The first rating developed by The American
National Standards Institute (ANSI) is a
procedure to test for the permeability to water: it consists
of boiling the tile in water and measuring its gain in weight
from the original dry state.
Four ratings have resulted from their studies and are classified
as such:
- non-vitreous - tile with
water absorption of more than 7.0 percent.
- semi-vitreous - tile
with water absorption of more than 3.0 percent, but not
more than 7.0 percent.
- vitreous - tile with water absorption of more
than 0.5 percent, but not more than 3.0 percent.
- impervious - tile with water absorption of
0.5 percent or less.
This means that the hardest tiles (sometimes referred
as "porcelain"), are the ones fired at a very high temperature
to achieve the impervious rating. These tiles will be the most
durable and easiest to clean simply because of the hardness.
The second rating, developed by The Porcelain Enamel
Institute (PEI), is the standard
for abrasion or wear of the tile. These are basic categories
but are valuable when selecting tile in a retail environment.
They are as follows:
-
walls only no foot traffic
- residential, low traffic
- all residential, medium commercial (interior
only)
- heavy commercial
- extra heavy commercial (interior or
exterior)
As you can see this is all very ambiguous. So how
do you tell one from the other when you go shopping for tile?
I will try to clear this up as much as I can for you.
Let me first say that all tile doesn't have to
be impervious or porcelain to be good quality tile. Some ceramics
can be rated 4 with an absorption rate of 2% and still function
fine in a residential setting. These tiles are still manufactured
because of design considerations. There are many designs available
in vitreous (ceramic) tiles that cannot be reproduced by the
high firing process necessary in impervious ( porcelain ) tiles.
However, if you are installing tile outdoors a frost-proof tile
is necessary. These are only the very hardest and least absorbent
tiles. The impervious ( porcelain ) tiles fit into this category
and are fine to put outdoors.
I have seen some vitreous ( ceramic ) tiles that
can be applied outdoors but they are becoming very few in number.
Some tell tale signs to look for to determine
an impervious (porcelain) tile:
- look for the little specs on the "bisque" porcelain
- "full-bodied" porcelains will have the color
going all the way through the tile
- look for a stamp called "Porcellanato" on
the back or on the carton (this is the Italian word for porcelain)
- if the stamp says monocoturra it is not porcelain
- the color of the clay body (bisque) is lighter
in color
I would like to sum up with my view of what makes
a porcelain or ceramic tile and provide you with some application
parameters.
Porcelain tiles:
They are fired at a very high temperature enabling a high solids
content. Some porcelains are full-bodied meaning the color
of the tile tile is solid throughout.
Other porcelains are: a porcelain bisque with an
altered surface appearance or a porcelain body that has been
glazed. For a tile to be considered impervious (porcelain) by ANSI standards
it must have an absorption rate of less than 0.5%.
The low absorption rate makes porcelain up to 6
times more frost resistant than a vitreous tile. Therefore outdoor
applications are possible.
Porcelain also has superior chip resistance making
it stronger and more durable in most cases than granite. Applications
in high traffic areas or kitchen countertops are no problem at
all.
Many porcelains offer the appearance of natural
stone without the maintenance.
Needless to say, this is why porcelain has become
very popular in recent years.
Ceramic tiles:
Ceramic tiles are characterized by a dark red or terra cotta
back with a fine glaze over them. They are fired at a lower temperature
which means they can be more brittle and contain only a surface
glaze.
However, there are many good quality ceramics with PEI ratings
of 3 or 4 that can provide excellent durability. They will have
a higher absorption rate so be careful not to use them outdoors.
From a design perspective though, you may want
to choose ceramic because many designs and colors that are not
available in porcelain tiles are available in ceramic tiles.
The main advantage of ceramic tile is that it is
easy to cut and handle. Score and break cutting boards are normally
sufficient. This makes ceramic the choice for bathroom walls
or kitchen backsplashes.
For example: If you were installing tile in an
upstairs bathroom, you would not need to walk up and down steps
to make every cut on a wetsaw.
Hope this has helped to clear some of the mystery.
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