Plastic Bag Education

Below is an explanation of  the most common terms and descriptions of the materials that are used to make plastic bags.  Our customers have found the plastic bag education page to be a valuable resource in figuring out the correct type and size of plastic bag they are looking to source.

Low Density Polyethylene (LDPE)

Polyethylene is the most commonly used plastic in the world. Low Density Polyethylene is the material used in most poly bags mainly because it provides great strength, clarity and flexibility.

High Density Polyethylene (HDPE)

High Density or HD bags are made out of a thin and light substance, which helps to lower cost of the bags as well as the freight. High Density bags are not as clear as Low Density poly bags however they are very strong, tear-resistant, and stiff. These bags are both strong and economical.

Cellophane:

Cellophane offers excellent film clarity for display. The cellophane film works as a barrier to preserve aromas and keeps food fresh. Cellophane also enhances the appearance of products. Cellophane however is not recommended for use in extreme temperatures.

Polypropylene:

Polypropylene has the highest clarity available. This is an excellent material to protect against moisture and vapors. It is suitable for food, crafts, photos, cards, and scented products. Polypropylene is the preferred option for display.

Bag Dimensions

Flat Bags

Flat Plastic bag specifications

How to figure out the plastic bag specifications to determine width and length of a flat plastic bag used as a cover or liner

Flat Poly Bags
W: Width
L: Length
Gauge: The gauge indicates the thickness of the bag. For more information check the conversion chart below

Gusseted Bags

gusseted plastic bag liner size diagram

How to figure out the size required for a gusseted plastic liner

Gusseted Poly Bags
W: Width
D: Depth (gusset x 2)
L: Length
Gauge: The gauge indicates the thickness of the bag. For more information check the conversion chart below

Round Container

round container

How to figure out the size of a plastic bag for a round container

Round Container Length: Add ½ of the diameter to the length plus 4″ for overhang. Choose next larger size for best fit. Width: Measure around the container top or multiply the diameter by 3.14, divide by 2 and add 2″ for a looser fit.

Cartons or Boxes

square box plastic bag size diagram

How to figure out the size of plastic bag or plastic liner required for a square box

For a Cover:
Add 3″ to the width and 3″ to the depth for a loose fit.
Add half of depth to the length.
Example:
W: 25″+3″= 28″
D: 20″+3″ = 23″
L: 40″ + 10″= 50″
Size to order: 28 x 23 x 50For a Inner Liner:Add 4″ to either width or depth. Add all the depth to the length plus a few inches for overlapping ends.
Example:
25 + 4 = 29
20 = 20
40 + 20= 60Size to order:
29 x 20 x 60

Conversion Chart

Gauge in Mil Gauge in Inches Gauge in Microns
.30 .0003 7.50
.35 .00035 8.75
.40 .00040 10.00
.45 .00045 11.25
.50 .00050 12.50
.55 .00055 12.50
.60 .00060 13.75
.65 .00065 15.00
.70 .00070 16.25
.75 .00075 17.50
.80 .00080 20.00
.85 .00085 21.25
.90 .00090 22.50
.95 .00095 23.75
.100 .00100 25.00

Liners Weight and Applications

Description LLDPE LDPE
Light 0.38 mils 1 or 1.25 mil
Medium 0.58 mils 1.5 or 2 mil
Heavy 0.78 mils 3 or 4 mil
X-Heavy 0.98 mils 5 or 6 mil

Glossary

Can Liner
Term used for garbage, trash or waste bags. Used in industrial, institutional and medical applications
Colors
Can liners come in standard colors: clear; black, white, gray, red, blue and yellow (Other colors available)
Food and Utility Bags
Small clear bags designed to hold a variety of small objects (e.g., bread, poultry, vegetables, etc)
Film Strength
Refers to the physical strength of the can liner. Some resins have a higher film strength than others. Our bags are made from highest quality resins, giving them the highest quality film in the market place.
Dart Drop Test
ASTM test used to determine the resistance of a bag to local failure or puncturing of the film.
Elmendorf Tear Test
ASTM test used to measure the resistance to tearing.
Wet Load Capacity
Measurement of how much wet weight a bag will hold.
Dry Load Capacity
Measurement of how much dry weight a bag will hold.
Gauge
Term used to describe thickness, LDPE and LLDPE bags are measured by mil thickness and HDPE bags are measured by micron thickness.
Mil
(One thousandth of an inch) Term used in the measurement of LDPE and LLDPE bags. One mil is .001”. Can liners range between .35 to 4.0 mil.
Micron
Term used in the measurement of HDPE bags. 25.4 microns equals .001”. 1,000 microns (M) = 1mm. HMW-HDPE can liners are 6 to 24 microns.
Resin
Short term for Polyethylene (PE) resin. The three types of PE resins are LDPE, LLDPE and HDPE (see below). Other plastics resins include vinyl, polypropylene, styrene and nylon.
LDPE
(Low Density Polyethylene) This resin was used with older bag technology. Resin has good clarity but weak film strength. Today it is used primarily for Food and Utility Bags.
LLDPE
(Linear Low Density Polyethylene) This is the primary type of resin used in modern can liner manufacturing technology. Bags made from LLDPE film provide excellent combination of film strength, puncture resistance and tear resistance.
HDPE
(High Molecular Weight-High Density Polyethylene) Bags made from HDPE resin provide excellent film strength and puncture resistance, but less tear resistance than LLDPE.
HAO
(Higher Alpha Olefin resin) A high-grade Hexene or Octane-based resin used in all of our LLD liners. The properties of this resin allow for a higher-quality can liner.
Butene
One of three types of LLDPE resin. Butene has weaker film-strength properties than Hexene or Octene.
Hexene
One of three types of LLDPE resin. We use Higher Alpha Olefin (High Grade Hexene) in the manufacturing of our bags. Properties include high film strength and increased tear resistance.
Octene
One of three types of LLDPE resin. We use Higher Alpha Olefin (High Grade Octene) in the manufacturing of our bags. Used in other applications because of its excellent physical properties.
Prime Resin
Refers to the usage of high-quality, “fresh from the reactor,” resin. We use only prime resins in all of the products we produce, unless specified otherwise.
Blended Resin
Refers to the combination of two or more types of resin.
Reprocessed Resin
Refers to resin that has been used at least once before. Can be post-industrial (scrap) or post-consumer (recycling). Property of resin is decreased each time it is reused.
Seal
Term used to describe bottom of a can liner. The three types of seals are flat, gusseted and star.
Flat Seal
Straight seal along bottom of a bag. Though Flat Seals are strong, they may have a tendency to leak from the corners.
Gusset Seals
A flat-style bag manufactured with both sides tucked in to form gussets. Has a tendency to leak from the center at gusset points where four layers of film meet two.
Star Seal
This multilayered seal is full gusseted and then folded prior to sealing, allowing for the contents to be evenly distributed.
Top-Side Dispenser Box
An innovative style of box that allows stacking in small spaces. It is just as easy to pull a can liner from the side as it is the top.
Individually Folded
Bags are separately folded, then stacked on top of one another. This allows the end-user to pull bags out of the box with much more ease vs. bulk-folded bags.
Cored Rolls
Bags are rolled together on cardboard cylinders.
Coreless Rolls
Can liners are rolled in groups of 25 or 50 per roll. There are 4 to 10 rolls per case. Rolls are perforated or interleaved.