Buying Guide: Trash Can Liners

You may be asking, "Why do I need a buying guide for trash bags - what's so difficult about buying them?"  Difficult?  Nothing really, but there actually is science behind them that you may not be aware of.

There are basically two steps to choosing a can liner:

  1. Understanding the plastic types and gauge
  2. Matching bag sizes to cans

Let's take a look at each of those steps.

Understanding the Plastic Types and Gauge

Linear Low-Density Can Liners (LLD) - these are best for rough or sharp objects and things that are heavy to extra-heavy, such as heavy food, boxes, cans, construction debris, sticks, yard trimmings and metal with sharp edges.  They are very strong and more resistant to tearing than high-density bags, but have a lower load limit.

High-Density Can Liners (Hi-D) - these are best for light-to-medium trash that is frequently changed.  Use for paper plates, cups, paper towels, grass, smooth heavy objects or food without sharp edges.  These bags are very strong and can handle a higher load capacity than the LLD bags but the tear more easily when punctured.

Gauge (Film Thickness) - Film thickness used to be the primary way to judge strength on can liners.  However, due to advances in the polymer blend formulations, today's can liners are now thinner and lighter, yet stronger and more durable than older bags.  Consequently, it has become acceptable to use terminology such as "Light" "Medium" "Heavy" and "Extra Heavy" although many manufacturers will still list gauge in the description of the item, either as mils (for low-density bags) or microns (for high-density bags).  Here's some basic comparisons of strength to gauge:

                             LLD Bags                                                                                                                           Hi-D Bags

       Strength Grade                   Gauge                                                                                 Strength Grade          Gauge

  • Light                             5-9 microns                                                                            Light                            .35-.44 mils
  • Medium                       10-12 microns                                                                        Medium                      .45-.57 mils
  • Heavy                           13-14 microns                                                                         Heavy                          .58-.69 mils
  • Extra-Heavy              15-17 microns                                                                         Extra-Heavy             .70-.89 mils
  •                                                                                                                                              XX-Heavy                  .90-1.14 mils
  •                                                                                                                                              Super                            1.15-1.39 mil
  • Super-Heavy              18-24 microns                                                                        Super-Heavy             1.40 mils and up

Matching Bag Sizes to Cans

If you know the gallon capacity of your container, you're off and running.  The gallon capacity will be listed in the description of the bag.  

But Wizard, whatever shall I do if I don't know the gallon capacity?  How will I ever find the right bag?  

I'm glad you asked.  (You know I would have told you anyway, but it's nice to be asked.)

Trash bags are measured by the width and length when laid flat - the first measurement is the width and the second is the length.  The width is the circumference of the container, divided by 2.  Length is the measurement from the top edge to the bottom edge of the container, plus 3 inches for overhang.

But Wizard, I hated math in school.  I don't remember how to find the circumference.

The circumference is the measurement all the way around the container, but there's another way to find it if you don't have a tape measure that long.  For a round container, measure the diameter across the top and multiply by 3.14 (Pi - Yumm!).  For a square container, it's the sum of the length of all four sides.  Divide whatever number you get by 2 to get the width of the bag.

One more thing that I want to mention is the bottom seal.  Most can liners will have a Star Seal.  This has become the industry standard because it is the strongest type of seal.  It conforms to any shape of container, distributes weight evenly inside the bag and has maximum carrying capacity.  There are two other types of seals - flat and gusset.  Flat seals are generally leak-proof, but they don't conform well to the shape of the receptacle and can be difficult to handle.  Gusset seals are manufactured with both sides of the bottom edge tucked in to form gussets.  The outer edges are reinforced with four layers of film, while the middle section has only two layers.  This causes a tendency to leak with wet trash.  Check the description of the bag you're buying to make sure it has a star seal.

Star Seal

Star Seal

Well, that's all for today.  I can't give away all my infinite knowledge at once.  Come back often for more gems!