How to Select Stretch Wrap - Frequently Asked Questions

What is the difference between stretch wrap and shrink wrap? 

• Shrink wrap is a poly plastic product that is applied with the use of a heat gun that heat shrinks the film so that it conforms securely around the product to which it is applied.  It's most common application is for storage and protection from the elements.  In short, shrink wrap is used to cover and protect product.
• Stretch wrap is a poly plastic product that is used most commonly to wrap pallets of boxes or other product.  It is stretchy with a strong elastic property and usually has a two-sided cling to is sticks to itself.  It does not need a heat gun or any other special equipment to be successfully applied.  In short, stretch wrap is used to contain product and hold them together.

 What is “gauge” and how do I know what gauge I need?

• Gauge is the most common measure of the thickness of stretch film (sometimes also measured in microns)
  100 gauge = 25.4 microns = .0254mm = .001in
• The higher the number, the thicker the film (100ga > 80ga > 60ga, etc)
• 80 gauge is the most common film, the “average” or “standard”
• Heavier gauge films are typically required for:

• Heavy loads, such as fasteners, machine parts, bags of mortar or mulch, etc.
• Uneven loads with more corners and angles (also known as B- or C-loads)
• Greater puncture potential
• Lighter gauge films are typically required for:
• Lighter loads, such as foam products, or light food products (snack foods like chips, etc)
• Even, square loads (also known as A-loads)
• Little to no puncture potential
• Film is typically available in gauges ranging from 40ga - 150ga
• Ultimately, the thickness needed is subjective.  Samples film, when available, is ideal to determine what works best for your needs.

What is the difference between bundling film, hand wrap and machine film?

• Bundling film has a smaller width (2”, 3” or 5”) and is hand applied
  
  
• Applications
• Securing long lengths of product, such as extruded metal, wood molding, PVC lengths, pipe, rebar, etc
• Bundling together multiple small boxes so they ship as a single unit
• Advantages
• Small width
• Similar application as tape but with no sticky residue
• Easy to apply and clean to remove
• Means of Application
• Standard Bundler – the most common bundling film, it comes on a 3” core and often ships with one plastic plug-in handle per case
• Extended Core– Comes on a 1” core which extends almost 5” beyond the film, creating a built-in handle for each roll.  Some ship with a rubber grip to fit over the extended core.
• QuikWrap – The most efficient and most ergonomic option, ships on a 1¾” core and with one black plug-in handle per case.  The handle end features a black rubber grip that rotates freely around a core, allowing for easy application and a secure fit into the core of the stretch wrap.

• Hand Wrap comes in 12”, 15”, 18”, 20” and 30” widths and is hand applied
• Applications
• Wrapping small pallets of average weight and evenly stacked product
• Large pallet wrapping, but not in large quantities per day
• Advantages
• Can wrap a full pallet without the large capital investment required by a stretch wrap machine
• Portable and can be used anywhere
• Means of Application
• Standard Hand Wrap – ships on a 3” core and is applied by hand or with hand dispenser such as the Nelson Better Wrapper  (12”, 15” and 18” widths)
• Extended Core Hand Wrap – ships on a 1” extended core (looks like a rolling pin) and is applied by hand (20” and 30” widths)

• Machine Stretch Film or Pallet Wrap most frequently comes in 20” or 30” widths, but is also available in 40”, 50” and 60” widths
• Applications
• Standard size skids but of heavy-weight product which require a high degree of stretch
• Environments that require multiple skids to be wrapped per hour throughout the day
• Semi-automated environments
• Advantages

• Machine wrap can obtain a stretch of over 250%, depending upon the film and the machine
• Saves time
• Greater efficiency and safety
• Saves money on stretch wrap by getting more stretch out of each roll
• Means of Application
• Semi-AutomaticStretch Wrap Machines range in price from $3900 and upward and offer a variety of options to best fit your production and budget needs
• Stretch Wrap Machines are generally not mobile and are restricted to a specific location within your warehouse

What is the difference between cast and blown film?

• Cast Film
• By far, the most commonly used film, particularly with stretch wrap machines and bundling film
• Easy, quiet release
• High Clarity
• Tear resistant
• Limited puncture resistance
• Best for even loads of average, near-average, or below average weight
• Blown Film
• Most often used with hand wraps
• Noisy unwind
• Hazy, low clarity
• High puncture resistance and toughness
• Best used for heavy, uneven loads, or those with high puncture potential

What other options are available with stretch film?
The most common non-stock options are:

• UVI – for long term outdoor storage
• One-Side Cling – Good for loads that deliver on flatbed trucks (such as mulch) so that the skids of product do not stick together and risk being torn
• Color – Stretch film can be made in various primary colors, both in tint and opaque

What is “gauge equivalent” or “replacement gauge” film?

• Up until a decade or two ago, the only real measure for stretch film was its gauge, or thickness.  As a result, certain gauges became associated with certain strengths and performance characteristics
• More recently, with the advances in technology, we are able to make thinner films that have the equivalent strength of thicker (higher gauge) films.  This enables us to provide you with a high quality film at a lower price because less material is used in the production of the film.  Our Extreme films are an example of this type of film.
• Gauge equivalent or replacement gauge films are best suited for even loads of average or below average weight.
• Despite the advances in production technology, the most common way of referring to film strength and performance is still the gauge.  80ga, however, now, may not necessarily refer to the actual thickness of the film, but to the relative performance – it will perform comparably to an actual 80ga film.

How to Package Mulch and Similar Landscaping Products

The packaging and shipping of mulch and related products has very specific requirements and needs. If these needs are not accommodated, it can lead to problems, inefficiency and waste. If they are accommodated, your operation will run that much smoother and more efficiently.

Bagging

In most cases, standard stock bags will not work for the bagging of mulch and related products.  Size is very subjective, as is the need for side gussets or a lay flat bag.  There are three characteristics, however, that most mulch and related operations prefer:

• Vented Bags
  Vents are simply holes in the bag that allow the product to breathe.  There are different types of vents, but following are the most common:
• Micro-Perforation - pinpoint holes in the bag spaced two inches in every direction.
• Butterfly - partial holes held to the film/bag by a tab and spaced according to the customer's requirements.
• Normal - 1/4" round holes, punched fully out of the bag, and spaced according to the customer's requirements.
• Non-Slip Material
  Most standard low-density polyethylene bags (or LDPE) have a somewhat slippery finish to them.  This can look good and isn't a problem in many industrial applications, but can present serious problems when trying to stack your bagged product, whether on a pallet or on a job site.  A Non-Slip material will increase the friction between the bags and allow them to be stacked without that problem.
• UVI/UVA Treated
  A UVI/UVA treatment will protect the bag and its contents from the harmful rays of the sun.  The standard UVI/UVA treatment is a 1.5% concentration which will ensure a shelf life of one year.  Higher concentrations will extend the shelf life accordingly.  This prevents both the deterioration of the bag over time as well as the degradation of the contents.  Contrary to what many believe, UVI/UVA treatments do not require that the material be any particular color, much less black.  They can be clear or any other color.  Typically, the main reason some users prefer their UVI/UVA treated material to be colored is so they can easily differentiate it from those materials that are not UVI/UVA treated.  UVI/UVA should not be used with film/bags that come in contact with agricultural chemicals or pesticides.

In most cases, finding bags that meet at least two of these criteria means that you'll be dealing with custom made bags, as opposed to stock.  Let us know what you need and we'll help you determine what will work best, and what kind of minimums, costs and lead times are involved.  For additional information on poly bag options and characteristics, look at our Poly Bag FAQ post.

Transporting and Storing

Whether it's moving on the back of a flatbed truck, sitting for a period of time on a job site or in a retail environment, how you store mulch or related products is equally as important as how you bag your product.  Following are two options to consider when transporting and storing mulch products:

• Slip Sheets
  Slip sheets are simply a piece of corrugated cardboard that goes between the pallet and your bagged product.  It's a simple thing, but very important in that it will help minimize the possibility of the bags on the bottom getting torn and damaged.
  
• Single-Side Cling Stretch Wrap
  Sometimes called shrink wrap, stretch wrap is the clear, thin, poly product that is used to wrap a skid of bags and secure it to the pallet.  Unlike most stretch wrap applications, skids of stretch wrap do not have nice, smooth sides.  The convex nature of a pallet of mulch bags means that these skids, when stacked on or in the back of a truck, will make contact with one another.  If you're using standard stretch wrap, which is a two-side cling, you run the very real risk of your skids sticking together and tearing one another as you move them.  Single-side cling film means that only the inner layer of the wrap has cling and the outer side does not, eliminating (or at least minimizing) this problem.
• Pallet Covers
  These are often used in conjunction with stretch wrap.  Essentially, they are large bags that are turned upside down and pulled over the pallet or stack of bags.  They can be colored and/or treated with UVI/UVA.  They serve to protect your product from weather or light damage, and with the UVI/UVA treatment, can protect your product from the damage caused by the sun as well.  They can be used over or under the stretch wrap (if used over, it can eliminate the need for single-side cling film, as addressed above), and can be re-used as well.  Pallet covers can also be fairly easily printed in order to publicize your brand.  For more information on pallet covers and how to measure for them, look at our previous post on that topic.
• UVI/UVA Protection
  A UVI/UVA treatment (as referenced above) can be added to both stretch wrap and pallet covers.

Whatever your products and your needs, contact us and let us know how we can assist you to make the most of the options that are available.  We can provide you with stock product options, custom quotes, and samples where needed.

Understanding Plastic Poly Bags

Frequently Asked Poly Bag Questions:

What different materials are most poly bags made of?

Which type of bag material do I need?

What type of bag size options are there?

How do I know what thickness I need for my poly bag?

What options are there for sealing a poly bag?

What is the best type of bag or tubing to use for shipping  sensitive electronics and components?

Guides to measuring for the correct bag size

Differences between polyethylene and polypropylene 

What different materials are most poly bags made of?

• Low Density Polyethylene (LDPE – also simply known as “poly”)
  This is probably the most common type of bag.  An example of LDPE bags would be your standard sandwich bags you buy at the grocery store.  It is flexible and tough, but is breakable, and comes in a variety of thicknesses and sizes.  Most LDPE bags are USDA and FDA approved for food storage.  Polyethylene is translucent and prohibits a greater amount of light from penetrating, subsequently making it the preferred choice for archival storage of printed materials.  It has a low static charge, meaning that it will attract less dirt, dust or other foreign elements than other materials.
• Linear Low Density Polyethylene (LLDPE)
  Similar in appearance and feel to LDPE, LLDPE is a stronger variant of a polyethylene bag.  It has more puncture resistance and resilience than LDPE, is very flexible and stretchy, offers better resistance to heat and cold, all while not needing to be as thick as a comparable strength LDPE bag.  It is not as easy to process as LDPE and can therefore be more expensive, has a lower gloss, and a narrower range for heat sealing.
• High Density Polyethylene (HDPE)
  HDPE is most commonly seen in retail bags like you get at the grocery or drug store, or in trash can liners.  It has very little clarity and is thinner and very “crinkly” compared to LDPE (standard poly) which is smoother and has very good clarity.  The advantage of HDPE is its high strength to density ratio – meaning that it can be very strong while still being very thin.  It has less flexibility than LDPE and can withstand higher temperatures for short periods.
• Polypropylene (polypro or LDPP)
  This is most common for food products and for presentation quality.  It is a high clarity bag that provides a protective barrier against moisture and vapors, which helps delay evaporation and dehydration to preserve freshness and taste of food products.  It is fully transparent.  They are ideal for food storage, clean room, electronics, and other applications.  It is stiffer and more “crinkly” than LDPE and has a slightly rougher surface.  It is not flexible or tear/puncture resistant.  All polypro bags meet FDA and USDA specifications.

Which type of bag material do I need?
What is most important to you:

Strength and resistance to tear/puncture	LLDPE, LDPE
Clarity and presentation	PolyPro
Flexibility and toughness	LDPE or LLDPE
Strength and affordability	HDPE
Food storage (long term)	PolyPro
Food storage (short term)	LDPE or PolyPro
Can/Bin liners	HDPE or LDPE
Retail merchandise bags	HDPE or LDPE
Affordability, effectiveness, and diversity of applications	LDPE
FDA/USDA approval	LDPE or PolyPro
Archival storage of printed materials	LDPE
Heat sealing	LDPE & LLDPE are ideal and most common. Others are dependent upon the machine and bag thickness

Please note that these are guidelines only, and that there are no definite rules. It all ultimately depends upon your application and individual needs. Samples can be helpful to enable you to determine what material works best for you.

What type of bag size options are there?

Lay Flat
Measured W x L
These bags only have two dimensions, width and length (always referred to in that order).  The width is also the measurement of the bag opening.  Lay flat bags are best for products that have very little thickness/depth.

 Gusseted

• Side Gussets
  Measured W x D x L
  These are the most common types of gusseted bag.  The gusset is the depth of the bag, giving it the ability to expand in order to contain larger contents with a significant thickness or depth.  The easiest example of a gusseted bag would be the brown lunch bags, which have side gussets.  Side gussets fold inward to allow the bag to collapse flat, but expand to allow for larger contents.  The measure of the gusset references the fully extended depth of the gusset.  These bags are available case-packed (individual bags) or on rolls (perforated), and are not available as reclosable/zip closure bags.
• Bottom Gussets
  Measured W x L + D
  These are best when you need a reclosable gusseted bag, one that may stand up on its own once filled, and where the contents may be heavier than average.  Bottom gussets expand at the bottom, rather than the sides.  The most common examples of bottom gusset bags are reclosable food/pet food products.  These are available case-packed only, and are available with reclosable/zip closure options.

How do I know what thickness I need for my poly bag?

Mil Thickness
Poly bags are measured by mil thickness.  1mil = .0254mm or .001in or 100 gauge.  For example, a standard retail sandwich bag is typically approx .75mil thick, while standard reclosable retail zip top bags are 1mil.  The larger the number, the thicker the material.  The thickness is usually denoted as either “2mil” or “.002”.

General Guidelines for LDPE Poly Bag Thickness

o   The heavier the contents, the thicker the bag

o   The greater the puncture potential, the thicker the bag

o   With polyethylene bags (LDPE ), greater thickness = lower clarity

Mil Thickness Suggestions for LDPE Bags

o   1mil        Lightweight, economical short term storage

o   1.5mil     Lightweight protection from dirt and moisture

o   2mil        Protection for shipping and storage

o   3mil        Additional protection for hardware, fasteners, and industrial components

o   4mil        Heavy duty protection with puncture potential

o   6mil        Extra heavy duty protection for high weight items and those with particularly high puncture potential

Determining thicknesses of can liners (HDPE, LLDPE)

o   .40 - .55 Mil – Regular Refuse

o   .55 - .65 Mil – Medium Refuse

o   .65 - .80 Mil – Heavy Refuse

o   1.5 – 2.0 Mil – Extra Heavy Refuse

What options are there for sealing a poly bag?

Heat Sealing
Heat sealers offer a secure seal for polyethylene and polypropylene bags up to 6mil thick and up to 24” wide.  Many heat sealers come with a 30-day warranty, require no warm-up period, and use electricity only when the sealing bar is down.  Options include hand sealers, manual foot-operated sealers, and automatic sealers, with or without trimmers.  Each heat sealer creates a seal that is both water-tight and air-tight.  Using a heat sealer creates a permanent seal that cannot be reused.

Reclosable/Zip Top Bags
Reclosable zip-top bags are lay flat or bottom-gusseted and range in thickness from 1mil to 6mil.  Most zip top bags are FDA approved and offered in polyethylene or polypropylene.  There are generally three types of zip top reclosable bags:

o   Standard Single-Track Reclosable Zip Tops
These offer a standard single zipper closure, similar to retail zip top sandwich bags

o   Double-Track Reclosable Zip Tops
These bags offer a double-zip closure that assures an extra-secure seal

o   Slider Top Reclosable Zip Tops
Slider top bags are ideal for bags that need to be accessed repeatedly.  They are easy to use and access, even with gloved hands.  The slider assures as much as possible that the seal is complete and secure.

Lip and Tape Closures
A lip and tape closure is similar to an envelope closure where there is a lip that extends over the opening of the bag and which has a tape strip that, when folded down to the bag, creates a seal.  Lip and tape closures can be permanent or reusable.

Draw String Closure
Double-pull drawstring bags open easily and provide a secure closure as well as a convenient means of hanging the bag.  They can be reused multiple times.  They are ideal for content that needs to be accessed repeatedly and easily and in a way that will eliminate fall-out possibility.

Ties and Tape
Common options include vinyl and paper twist ties as well as nylon cable ties, self-locking adjustable plastic ties, and bag sealing tape.  Each of these offers an easy and affordable means of sealing any type of bag.  Of these, only the nylon cable ties and the bag sealing tape are not reusable.

What is the best type of bag or tubing to use for shipping sensitive electronics and components?

Metallic Static Shielding Bags

Best for static sensitive components that are handled outside of an Electrostatic Protected Area (EPA).  These form an effective Faraday Cage around the contents (a Faraday Cage is when the bag is slightly conductive and forms a shield around the contents to protect any discharges from being deposited on to the protected device during the handling process).  These bags should not be creased or used if there are any tears or punctures as it can reduce the integrity of the shield/Faraday Cage.  The effectiveness of the bag can also deteriorate with use, so when in doubt, it is best to use new bags.
Our static shielding bags meet the electrical and physical requirements of ANSI/ESD S541 and are EIA 625 and ANSI/ESD S20.20 program compliant.  Tested per MIL-STD3010 4046 and ANSI/ESD STM11.11.

BlackConductive Bags
These bags should only be used in an Electrostatic Protected Area (EPA) and while the handler is grounded.  It is possible that contents could be damaged by contact with an electrostatic discharge (ESD – an uncontrolled surge of static between objects with different voltage).
Our black conductive bags meet the requirements of MIL-P-82646 Rev B

Pink Anti-Static (PAS) Bags
PAS bags are the only acceptable poly bag in an electrostatic protected area and offer no effective protection against a contact electrostatic discharge.  They are best used for non-static sensitive components, such as nuts and bolts.  Standard poly bags may generate and hold static charges greater than 10,000v, making the PAS bags a highly practical option.  PAS bags are also amine-free.  The effectiveness of anti-static bags can deteriorate over time, so when in doubt, it is best to use new bags.
Our PAS bags meet the static decay requirements of MIL-PRF-81705E, Type II and EIA-541.  Bags 4mil and thicker are engineered to provide a surface resistivity less than 1x1012 ohms/sq.

Guides to measuring for the correct bag size:

Polyethylene vs Polypropylene

	Polyethylene	Polypropylene
Clarity	Good (decreasing with thickness)	Excellent
	Translucent (prohibits more light)	Transparent
FDA/USDA Approved	Yes	Yes
Heat Sealable	Yes	Yes
Flexible	Yes	No
Puncture Resistance	Good (depending upon thickness)	Fair
Food Storage	Good	Excellent
Stock Thicknesses	1 mil – 6mil	.8mil – 3mil (1.5mil standard)
Archival Storage	Excellent	Good
Surface Texture	Smooth	Rough (relatively)
Static Charge	Low	Higher
Chemical Resistance	Good	Excellent
Melting Point	Low	High

Contact us today for more information and to answer any questions you may have regarding what bag type will work best for your needs and your budget.  We have a wide variety of stock bags and can custom make almost anything, depending upon your budget and quantity needs.  Look at our post on custom and printed bags for more information on this option.

Printed and Custom Poly Bags

Minimum Quantities and Custom Poly Bags
When ordering custom size and/or printed poly bags, the minimum order is probably the most significant consideration (other than price).  How this minimum quantity is determined is unique compared to other products your business may purchase and is helpful to understand.  Where most minimums are determined by a number of cases or individual units, poly bag minimums can vary and are determined by the weight of the source material (poly resins - Step 1 in the image below).  This results in two fairly simple rules:

• Larger and/or thicker bags will result in a smaller minimum quantity
• Smaller and/or thinner bags will result in a larger minimum quantity

The smallest minimum with most domestic manufacturers is usually 1000 lbs, though some go as low as 500 lbs.  The number of bags you can make from 1000 pounds of resin will vary from very high with a 4" x 6" 2mil bag (over 90,000 bags) to much less with a 51" x 49" x 73" 6mil bag (under 1000 bags). Additionally, as your minimum increases, your costs will typically decrease - this follows the same general "bulk order" rule of any transaction.

The diagram below is an illustration of how the manufacturing process works, which may help you better understand how custom bags are made and minimums determined.  The rolls of poly, Step 10, are then taken to other machines for cutting and sealing into the appropriate bag sizes.

More technical information on this manufacturing process as well as this source image can be found here.

Colored Bags
Most stock bags are clear, so if you need a custom color, you will be bound to the same rules as if it was a custom sized bag, even if it is a common stock size, because the bags have to be manufactured just for this purpose.  Colored bag minimums may be even higher because it requires more work and the colored resin material is simply not as common as the clear.  For example, the manufacturing line (see image above) must be purged of the colored material following production, which adds labor and time and subsequently can increase the cost.  As a result, custom colored bags may require a higher minimum quantity than a comparable clear bag of the same size.

Custom Printing Options
Most custom printing is done in-line (between steps 9 and 10, or after step 10 in the image above), meaning that the poly material is printed before it is made in to a bag.  Rarely, if ever, are bags printed post-production.  This means that you'll be held to the same rules as a standard custom bag, noted above, even though the bag you want printed may be a very common stock size.

Printed bags also have the additional charge of having the artwork done and the printing plates made.  This can range anywhere from around $200 and up, depending upon the complexity of the artwork and the numbers of colors involved.

There are two general types of printing options:

• Registered Print
  This is the most common, where you choose how many images will be on the bag and you specify the location (typically centered on the face of the bag).
• Random Repeat
  This is not as common for logos and graphics, but is most seen with generic warnings or ingredients.  Random repeat simply means that the bag will be printed at random locations on the bag and with somewhat random spacing.  An example would be a suffocation warning.  As a result, some of the print may be partial as it happens to fall on the poly sheeting in a place where it is cut to make the sheeting in to a bag.

The only way to know for certain what your minimums will be is to request a quote.  This will allow all of the variables to be factored in.  Contact us today and let us know what you need and we will help you determine what will work best for your needs and your budget.