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Application
How will the area to be carpeted be used? What
are your trying to acomplish by carpeting the space? If the purpose is a hardy
floor covering to absorb sound and make passage safer yet must endure a lot of
traffic you will go towards the multilevel loop carpets. If the pupose is to
soften the room and you may be living on the carpet you would want to select a
soft dense cut pile carpeting.
Design
The design of a carpet is the combination of the colors and
textures that compose the face of the carpet structure. Some are more
apropriate for high traffic and others can create a soft comfortable feel. The
selection process should first define the application of the carpet.
Construction
The construction of carpet combines yarn and other
materials in a variety of ways. Most carpet in use today is tufted carpeting.
This process uses a large loom that has what is similar to sewing machine
needles arranged in a 6 foot to 12 foot wide array. These needles basically sew
carpet yarn into a backing material. The process leaves loops of a
pre-determined length set down in a continuous process. These yarn loops are
then glued to the backing material and then the carpet may go through additional
processing to create other surface textures.
A second method of carpet construction is the age old
original woven carpeting.
What is the Basic Difference Between Tufted and Woven
Construction?
Tufted is the most common method for
both wool and nylon carpet. Pile yarns are punched through a primary backing
fabric in needles to form loops. An adhesive coating, usually latex, is applied
to the reverse side to anchor tufts in position and to laminate a secondary
backing fabric. Many patterns and textures are available including cut, loop,
cut & loop, and sliding needlebar.
Woven can be used for both wool and
nylon carpet. Pile yarns and backings are woven at the same time from a system
of warp (length) and weft (width) yarns, which means there is no secondary
backing. Pile yarns are always part of the warp system on the loom. More
versatile patterns and textures are available.
From the end users viewpoint the differences are noticed in the pile or
the yarn surface of the carpeting. Carpet pile is divided into three categories;
Loop, Cut Pile and a combination of the two. How these surfaces are constructed
varies a bit, so lets look at the surface appearance first.
Pile Types
Loop Pile
Yarn is stitched into a heavy material called the backing. The loops vary in
height and width according to the stitch rate and space between stitches. The
pile is very durable because each loop of yarn is anchored through the backing
of the carpeting at both ends. This makes a long lasting face construction.
With both ends of the yarn anchored in the backing the yarn holds its twist and
acts like a spring, bouncing back after traffic over and over.
Level Loop Pile 
When the stitch rates and loop lengths are consistent it forms a pile with
a very level surface in which all the loops are the same height, hence the name
level loop.
Multi Level or
Sculptured Loop Pile
Loops are tufted with different heights creating a pattern of lows and highs.
Sculptured Loop
Pile 
Cut pile
In this type of construction the loops that were
tufted are cut during the manufacturing process. What remains on the face is the
ends of the yarn. This produces a softer feel and a different look. The downside
is that cut pile carpet will not perform as well as loop carpeting. The ends of
the yarns will unravel over time and mushroom and mat down. This process can be
slowed by proper maintenance but it will occur over time regardless of how well
the carpet is maintained. The velvet plush has very little if any yarn twist
making it the softest feel of any pile.
Saxony Cut Pile
This variation of the cut pile retains the yarns individual twists. The pile
itself shows the yarn ends. Another variation is the shag carpet that was
popular in the middle of the 20th century.
  
Frise' Cut Pile 
This is another variation of the cut pile carpeting where the ends of the
yarns are given a twist adding texture to the surface. This helps to hide foot
traffic and wear.
Shag Pile
This is like the Saxony cut pile but the yarns are longer and
thicker. Some shags have a look like mops they are so long and thick.
Combination Cut and Loop
 
This
type of pile is formed by combining loop and cut tufts and enables all kinds of
designs and patterns to be formed by the arrangement of loops and tufts.
During manufacturing, the pile is made with
looped areas that are longer than others and these longer loops are cut to the
same height as the other loops to give a flat surface or to a different height
to give a sculptured surface.
Pile Components
After yarn, pile construction is the second
qualitative factor in carpets. The technical design of the pile is what gives it
its performance in terms of appearance, durability and wear-resistance.
Five parameters dictate the parameters: yarn
count, pile weight, gauge/rows, stitches/picks and pile height.
The specific technical expertise and know-how of
each carpet manufacturer are brought to bear on pile construction: this means a
harmonious combination of these 5 parameters to obtain a qualitative level
designed to meet the usage and traffic conditions for which the carpet is
intended.
As the most widely produced type, tufted carpets
can be used to illustrate the main points in understanding how pile is
constructed.
Fibers are covered more extensively in the Fibers
section of this site. For our construction considerations we need to know that
fibers are combined to form bundles of fibers we call yarn. It is these yarns
that are used to make carpeting.
When we consider the fiber that composes yarn it
will fall into the natural and synthetic categories. Then we need to consider
weather it is continuous filament or staple yarns. Continuous filaments are
found only in silk natural fibers, and Synthetic fibers. These fibers of both
types are then twisted together to form the bundle that composes the yarn.
Yarn
After the fibers or filaments are bundled
together into yarns they are stretched to align the molecules and improve the
strength of the yarn. The yarn is sometimes twisted, sometimes crimped and then
set with heat so it will retain its shape and twist.
Yarns can also be twisted together to make larger
yarn strands for a different look.
Yarn can be dyed when it is extruded in the case
of synthetic fibers, after it is made into yarn, or after it is constructed into
carpeting.
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| YARN COUNT
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Yarn count is basically the
number of fibers in the strand of yarn.
With fine yarn, it will be possible to
implant a large number of tufts per square meter; the coarser the yarn,
the fewer the number of tufts.
Yarn count – selected to take account of
other considerations such as appearance, comfort and use determines
carpet density.
PILE HEIGHT
Pile height means the thickness of the
pile above the primary backing. It is measured in millimeters. In some
structures, particularly cut pile, the pile height may be substantial,
10 to 20 mm, or more. Obtaining pile thickness is technically easy as it
is merely a question of putting more material into the pile height.
The problem is to build a pile which can
maintain its initial pile height for a reasonable length of time without
premature flattening. As a general rule, the higher the pile, the
greater the number of stitches and density necessary.
When considering pile height, it is
important to consider the pile weight and to analyze how this weight is
distributed between the height, the gauge and the number of stitches.
Pile height must work in conjunction with the gauge and the number of
stitches. |
The weight within the backing is of
interest as it affects tuft bind. However, the only meaningful value is
the usable weight, since this makes up the wearing surface. |
PILE WEIGHT
Pile weight is the total weight of the
material used to form the pile itself. In other words it is the weight
of the yarns in the carpet.
The weight of the yarn itself is not all
you should be concerned with. What is more important is how that yarn is
composed into the carpet face. This can be understood better by
comparing 4 factors – yarn count, height, gauge and stitch rate.
Luxury carpets with a high, very dense
cut pile use more yarn than low pile height, loop carpets with medium
gauge and stitch rates.
Pile weight is expressed in two ways, and
measured in grams per square meter.
- TOTAL weight: the mass of material in
the pile including the part within the backing.
- USABLE weight: the mass of material
located above the primary backing, and which can be measured by
shearing.
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Gauge & Stitch Rate
Top: sectional view of a
fine gauge. Bottom: sectional view of a coarse gauge
Top: sectional view of a
high stitch rate. Bottom: sectional view of a low stitch rate.
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GAUGE, STITCH RATE
AND DENSITY
Gauge is the distance between the tufting
needles. On its own gauge is not a sufficiently accurate indicator of
pile density.
If the yarn count used with the 5/64th"
gauge is, for example, 1 200 Dtex, and the same yarn is used with a
5/32nd" gauge, it is obvious the pile will have a lower density as it
will have only half as many rows and will thus contain less pile
material.
If, on the other hand, a 2 400 Dtex yarn
is used with the 5/32nd" gauge, although there will be only half the
number of rows each tuft will be twice as thick. In this case, density –
and weight – would be identical.
Any analysis of density must therefore
consider both the gauge and the count of the yarn, as shown in the
facing diagrams.
It might also seem obvious that the
greater the number of tufts the higher the density.
For identical gauges, this is perfectly
true. Between two 1/10 g carpets with the same pile height, made
with the same yarn and having respectively 156 000 and 187 000 tufts per
square meter, this is a significant comparison to make. The higher
number of tufts in the second carpet means that the stitch rate is
higher, giving a higher pile weight and density.
If the gauges are different, however,
this comparison is meaningless, as the number of tufts is a function of
the gauge. A coarse gauge means a small number of thick tufts; a fine
gauge means a high number of fine tufts.
1) A good combination of a fine yarn and
a fine gauge giving a well constructed dense carpet
2) A good combination of a coarse yarn
and a coarse gauge, giving a well constructed carpet
3) A bad combination of a fine yarn and
coarse gauge, giving a badly constructed carpet which is too open and
not sufficiently dense.
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Gauge|
(inches) |
Gauge
(in mm) |
Needles per meter |
| 5/16
1/4
3/16
5/32
9/64
1/8
1/10
5/64
1/16 |
7.93
mm
6.35 mm
4.76 mm
3.97 mm
3.57 mm
3.18 mm
2.54 mm
1.98 mm
1.59 mm |
126
157
210
252
280
315
394
504
630 |
The principal gauges are shown above.
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GAUGE & STITCH RATE
Pile stitch rate is measured in two ways:
across the width and along the length of the carpet.
Across the width
On tufting machines the space between the
needles is defined by precise standards. The space between needles is
given in fractions of an inch (1 inch = 25.4 mm). This is called the
GAUGE.
If the gauge is known, the number of
needles per metro can be calculated using the following formula:
1,000/g x 25.4 = no. of needles/metro
example: gauge = g = 5/32nds
1 metro = 1000 mm
(1O00 x 32) / (5 x 25.4) = 252
Depending on the gauge, tufting machines
comprise a number of needles in a range from 126 to 630 in a 1 metro
width, and from 504 to 2520 in a 4 metro width.
Each needle inserts a tuft which
corresponds to one stitch. This means that, with a 1/10th gauge, for
example, for every metro there will be 394 needles so 394 tufts
inserted.
Changing the gauge allows the number of
tufts to be varied to produce highly differing structures, from the
finest to the coarsest, in varying densities, depending on the
appearance and the quality required.
The foregoing introduces the notion of
yarn count, as it is impossible to dissociate gauge and yarn count. Yarn
count should increase as the space between the needles increases. If the
yarn is too fine for the gauge, the number of rows will be insufficient,
resulting in an open, weak pile, with low resilience and an unattractive
appearance.
Along the length
Tufts along the length are expressed as
the number of stitches per linear meter or decimeter. Stitches are
determined by the rate at which the backing, in which the rows of tufts
are inserted, is fed through the tufting machine.
Generally, stitch rates should be the
same longitudinally as laterally. If the gauge is, for instance,
1/8th", this means 315 tufts per meter; the longitudinal stitch rate
should be approximately the same. If it is lower, the pile will be
excessively open and will appear furrowed. Frequently, however, it is
higher as this gives a higher pile density.
Pile density stems from the number of
tufts per meter and is calculated by multiplying the number of rows
(gauge) by the stitch rate. Whilst the gauge is normally given, the
number of stitches is frequently not supplied although it is an
important item of information.
To calculate the stitch rate, divide the
total number of tufts per meter by the number of rows. For example, a
100 000 tufts/m' floorcovering with a 1/8" gauge has 315 rows. 100 000
divided by 315 = 317 stitches/meter – giving an appropriate
construction.
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Backing
Carpet Backing is a woven sheet of cloth like heavy material that is
used to build tufted carpet. It is the medium the needles stitch through
when tufting. Backing has normally been composed of jute material that
looks a lot like the old burlap bags that used be common.
The sheet of backing that the tufting occurs in is the primary
backing. After the yarn is tufted into the carpeting the material is
coated with latex or another type of glue and a second sheet the
secondary backing is adhered to the first. This helps lock all the
fibers in place and stiffens the carpet and makes it more dimensionally
stable.
Newer backing material is made of nylon or polypropylene. These are
less likely to rot in case of damp conditions and do not give off tannin
when wet , that can cause browning out and permanent staining to the
face yarn. |
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Installation
Experienced Contractor
Always review the qualifications of the
installer provider to be sure that they have a good track record and have
performed in your local area.
Padding (Cushion)
Padding is an important foundation to
your new carpet. Cheap padding can cause your expensive carpet to wear out
faster, so you won't be saving anything. The Carpet and Rug Institute guideline
for carpet pad is that it should never exceed 7/16 inch in thickness.
When you walk on your carpet, it bends
beneath your weight. The thicker the pad, the more the carpet flexes beneath
your weight. The thicker the pad, the faster your carpet wears out, so get the
thinnest, most dense pad you can. I recommend a 3/8 inch, 8 lb. density rebonded
urethane pad.
Certified Installer (CRI guideline)
It is important that the installer is
certified,
and knows and adheres to the CRI guidelines. As an inspector, the most common
installation-related defect I see is failure to use a power stretcher to install
the carpet. A knee kicker is not a power stretcher. A power stretcher is a
device that extends from one wall to the other with a lever utilized to
accomplish the stretch. Restretching can be expensive, so make sure your
original installation is done with a power stretcher.
Face Fiber
The fiber of the nap in your carpet is
of great importance. The most common carpet fibers are nylon, wool, polyester,
acrylic, and olefin (Polypropylene). Currently, nylon makes up 60% of the
market, olefin 30%, polyester 8%, acrylic 1%, and wool 1%.
The use of olefin is gaining in
popularity, but it has many drawbacks. It looks great in the showroom, just like
nylon, but it has extremely poor resilience and will "ugly out" due to matting
and crushing in a very short time. It also has a very low melting point, and
will melt from the friction of dragging a piece of furniture across it. The
retailer may tell you that it is easy to clean olefin, and compared to silk, it
is. But compared with nylon it is very difficult to clean, especially if you
have greasy or oily stains. It is also difficult to vacuum hair, lint, or thread
from olefin. I'm not even going to mention any advantage to olefin, except its
resistance to bleach, because its disadvantages so far outweigh the advantages.
It's just not worth your investment - stay away from olefin (polypropylene).
Health Data:
Some people experience allergic or flu
like symptoms, headaches, or respiratory problems which they associate with the
installation, cleaning, or removal of carpet or other interior renovation
materials. If these or other symptoms occur, notify your physician of the
symptoms and all materials involved.
Sensitivity:
Persons who are
allergy-prone or sensitive to odors or chemicals should avoid the area or leave
the premises when these materials are being installed or removed.
Note:
You can reduce your exposure to most
chemical emissions when carpets and other interior renovating materials are
installed, cleaned, or removed by increasing the amount of fresh air ventilation
for at least 72 hours. (See Installation and Maintenance guidelines or ask for
Owner's Manual.)
Basic Installation
Guidlines:
- Vacuum old carpet before removal
- Vacuum floor after carpet and pad
have been removed
- Always ventilate with fresh air
(open doors and/or windows, use exhaust fans, etc) during all phases of
installation and for at least 72 hours thereafter.
- If adhesives and/or pad are used,
request those which have low chemical emissions
- Follow detailed installation
guidelines from manufacturer or from carpet and rug institute.
The manufacturer of this carpet
participates in a program which seeks to develop ways to reduce emissions by
testing samples of carpet. With fresh air, ventilation, most carpet emissions
are substantially reduced within 48-72 hours after installation.
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