Learn More About
 Plastic Bags
  
Plastic Bags    
What are poly bags?  

"Poly" refers to polyethylene or polypropylene. Both are commonly used to make plastic bags.
 

 
What are the differences between polyethylene bags and polypropylene bags?  

Polyethylene is flexible, transparent, and heat sealable, which enables it to be folded and sealed into many types of bags. Polypropylene bags provide a highly protective barrier against moisture and vapors. It is non-porous, super-clear, non-stretching and generally more rigid than polyethylene.
 
 

 
What are cellophane bags?  
Cellophane bags are made from a crystal clear film and are great for food packaging. They provide a great way to present a product without covering it up. In addition, the barriers preserve freshness and contain odors.
  		 
What is the difference between Polypropylene and Cellophane?  
Polypropylene is a type of plastic generated from by-products of the petrochemical industry. Cello is produced from wood pulp. Polypropylene is a moisture barrier, while Cellulose film needs coatings for barrier properties. Cellulose films can vary the coating to have differing moisture barriers. Polypropylene is more flexible than cellophane.
  		 
Low-Density Polyethylene  

LDPE is porous and somewhat stretchable. It is suitable for everyday packaging needs and all-purpose trash collection.

Low Density Polyethylene examples: retail bags, shrink wrap, garment bags. Flexible, softer than high-density polyethylene. Waxy feel.
 

 
High-Density Polyethylene  

High Density Polyethylene (HDPE) is non-porous, non-stretching and just as strong as low density bags that are twice as thick. It is suitable for general packaging applications and trash collection that doesn't include sharp objects.

High Density Polyethylene examples: t-shirt bags, poly notion bags, crinkly department store bags. Thinner, less rigid than low-density polyethylene. Film has a crinkly feel.
 

 
Choosing the best gauge for your needs  

1 mil - used for dust protection, small parts, stationery, and items with an irregular shape. Common example: grocery store produce bags.
1.5 mil - used for moisture protection, clothing, nuts, candy, and other food items
2 mil - used for protecting items in shipment; parts and collectibles (stamps, coins, cards). Common example: Ziplock bags.
3 mil - used for items requiring added strength; tools, hardware, metal fasteners, furniture
4 mil - used for storage covers, gears, bolts, auto parts, and heavy items with sharp corners
Above 4 mil - used for extra, extra heavy duty

Note: the heavier the gauge, the milkier the plastic.
 

 
Measuring a poly bag  

Width is measured from "front" (face) inside seam to inside seam.
Length is measure from the top edge to the bottom fold.
Opening is in the width dimension.
Gusset (or depth) is measured from "side" inside seam to inside seam.

Bag measurements are usually stated as
W x L x G, or W x L (without gusset).

The first measurement is face width, second measurement is length, top to bottom, and third measurement is gusseted dimension.

 
What is a gusset?  
A gusset is a fold in the bag that enlarges the size of the bag when opened. It can be made as a side or bottom gusset.  
Disclaimer: The data presented in this document is for reference only. It was compiled primarily from outside sources and is offered to our customers as a means of comparing the characteristics of products offered by WAMACO Distributors Ltd.