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Why Isn't Gauge
Always Important?
Film thickness is no longer a satisfactory
standard for judging overall strength. The development of improved
LLDPE resin in the liner industry has completely changed the
standard method for selecting the correct Can Liners. These
materials have allowed manufacturers to produce thinner, lighter
trash bags which are stronger and more durable than the thicker
bags previously made from low density resin. This is why gauge is
no longer an effective way to determine liner strength. Instead of
stating actual thickness, it is now generally accepted to use
terminology such as "Light", "Medium",
"Heavy", and "Extra Heavy". (See comparison
table below.)
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General
Industry Strength Rating |
Linear
Low Density Mil Thickness Range |
Old Low
Density Strength Range |
Light (L)
Medium (M)
Heavy (H)
Heavy Plus (H+)
Extra Heavy (XH)
Extra Extra Heavy (XXH) |
.35
to .50
.45 to .75
.60 to 1.0
.74 to 1.5
1.3
1.3 to 2.0 |
1.25
1.5
2.0
2.5
3.0
4.0 |
| Each manufacturer
has its own blend formulations, so the proportions of these materials
vary from one producer to another. The best way to determine
the correct liner is to actually test some suggested samples. |
Definitions
It's important to know a little bit about what Can Liners are
actually made of, and how thicknesses are measured. That way
you can determine which of the polyethylene resins and liner
gauges will work best for your particular application.
Resin- The basic raw material from which Can Liners
are made. There are 3 types of resins: Low Density, Linear Low
Density and High Density Polyethylene.
Linear Low Density Polyethylene- This resin is
highly puncture and tear resistant. These properties make this
the best choice for applications where additional strength and
stretch are required. Works well for waste with sharp or jagged
edges.
High Density Polyethylene- Liners made from this
resin are generally available in lower gauges, and are more temperature
resistant.
Low Density Polyethylene- An older resin still
used mainly in lower end utility liners. It has largely been
replaced by Linear Low Density Polyethylene. Pitt Plastics does
not use this resin in any of our Can Liners!
Post-Consumer and Post-Industrial Polyethylene- This
is made from recycled post-consumer plastics such as milk jugs
and industrial scraps. These are reprocessed and blended with
other types of resins to produce new high quality liners.
Gauge- A term used to describe the thickness of
a liner. Low density liners are measured in mils, while High
Density liners are generally measured in microns.
Mil- Measurement based on thousandths of an inch
(.000). For example, a .55 mil bag would be 55 thousandths of
an inch thick. Common low density liners range from .37 to 1.8
mil in thickness.
Micron- Based on one hundred thousandths of an
inch (.000000). High Density liners usually range from 6 to 22
microns in thickness. |
| Different
Types of Can Liner Seals |
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Star
Seal (or X-Seal)
The star seal has become the most common type of seal in the
market today. Designed without gussets, the star seal eliminates
gaps along the seal where leaks can occur. This unique design
allows the bag to conform more easily to the shape of the container
and distributes the weight of the refuse evenly around the bag.
Star seal liners maximize the bag's carrying capacity and virtually
eliminate leaks. Star Seal liners are designated in two dimensions,
i.e., 40x46. |
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Gusseted
Seal
A flat style bag manufactured
with both sides tucked in to form gussets. Where indented, the
bag has to be sealed through four layers of film, while the middle
of the bag has only two layers. This leads to an inherently weak
bottom seal. Gusseted seal liners are designated in three dimensions,
i.e., 23x17x46. |
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Flat
Seal
Just as the name infers, a
flat seal is simply a two-
dimensional bag with a bottom seal. Flat seal bags are generally
leak-proof, but are very clumsy to handle. Also, they do not
conform very well to the shape of most trash receptacles. Flat
seal liners are designated in two dimensions, i.e., 40x46. |
Advantages of Linear Low Density Can Liners
1. Maximum puncture and stretch
resistance compared to High Density
2. Multi-purpose applications
3. Most prevalent type of film used in the industry today.
4. Manufactured in a wide variety of colors.
5. Compared to traditional low density film, linear low can be
run at a lighter gauge with equal strength.
Advantages
of High Density Can Liners
1. HMW/HD liners are about 3 times stronger and more durable
than ordinary polyethylene liners of the same thickness.
2. HMW/HD liners require two-thirds less petroleum based raw
material to manufacture. Accordingly, they can be made about
one-third the thickness of ordinary low density polyethylene
liners, so they require only about one-third the ordinary shipping,
storage and warehousing cost.
3. Substantial cost savings per liner.
4. When they are properly made, HMW/HD liners will rarely "zipper"
if punctured.
5. Extremely wide range of temperature resistance from -40 degrees
F to +212 degrees F (boiling).
6. USDA and FDA approved (natural colored liners). |
|
Mil Thickness |
Approximate
Micron Equivalent |
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0.23
0.27
0.31
0.35
0.39
0.43
0.47
0.51
0.55
0.59 |
6
7
8
9
10
11
12
13
14
15 |
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| Mil Thickness |
Approximate
Micron Equivalent |
0.62
0.66
0.70
0.74
0.78
0.82
0.86
0.90
0.94
0.98 |
16
17
18
19
20
21
22
23
24
25 |
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How to Convert Microns to Mils
To convert microns to mils, divide the micron by 25.4 to arrive
at true mil thickness.
7 Microns ÷ 25.4 = .28 Mil
34 Microns ÷ 25.4 = 1.34 Mil
How
to Convert Mils to Microns
To convert mil to microns, multiply the mil by 25.4 to arrive
at true micron thickness.
1 Mil = 25.4 Microns
.31 Mil x 25.4 = 7.0 Microns
.74 Mil x 25.4 = 18.8 Microns
How
to Figure Case Weights
Linear Low
Length x Width x Mil ÷ 15=Lbs./1000 bags
High Density
Length x Width x Mic x .0027034=Lbs./1000 bags |
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Measuring
for Correct Can Liner Size
BAG WIDTH:
Use one half of the outer circumference of the container.
BAG LENGTH: Use the height of the
container, plus one half of the diameter of the container bottom,
plus 3 inches (for overhang). For square or rectangular containers,
use the diagonal of the container bottom, rather than the diameter.
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