If you are going to take the time and spend the money to shrink wrap your packages, you ought to make sure they look good. But what kind of film should I use? How thick should the shrink wrap be? And how wide a roll should I buy? These are all important questions. Read on to get the answers.
1 Shrink Wrap isn’t Stretch Wrap
Many people use the terms interchangeably, but the two products are not the same. Shrink Wrap is a thin plastic film that shrinks or contracts around a product when exposed to heat. Stretch Wrap is a thin plastic film that is used to contain loads that are stacked on a pallet.
2 PVC or Polyolefin Shrink Film
PVC stands for polyvinyl chloride. The benefits of PVC shrink film include clarity, gloss/shine and the ability to impart very little shrink force on to the product being wrapped. Some common brand names are Reynolon and Syfan. Depending on the formulation, it can be ideal for wrapping flimsy products that easily deform like air conditioning filters and calendars. Some drawbacks of PVC include the fact that it hardens and becomes brittle when cold and it begins shrinking at warm warehouse temperatures meaning that in the right conditions it can shrink on the roll before it is ever used to wrap a product. Also, and most importantly, when it comes in contact with a bare seal wire, PVC releases small amounts of hydrogen chloride in to the air. Proper machine maintenance is critical when using PVC shrink film.
PVC was once the most common kind of shrink film but a number of years ago it was replaced by Polyolefin shrink film.
Common polyolefin shrink films include Cryovac, Sealed Air Opti, Bollore and Clysar. Polyolefin film can be used for almost every kind of application including toys, sporting goods, printed wrap, stationery and cards. Also, polyolefin is approved by the FDA for direct contact with food. When polyolefin comes in contact with a bare seal wire, it gives off carbon dioxide gas and water vapor. The main drawback of polyolefin shrink film is that it imparts a lot more shrink force on the product being wrapped. It will pull so tight that it can deform chipboard boxes and calendars. Other than that, it’s the go-to film for almost any application.
3 Measure Your Product
The standard formula for calculating the centerfolded film size for a package to be run on a manual or semi-automatic L-Bar sealer is:
(Width + Height) + 2 = Recommended Roll Width
Let’s say you are going to wrap a ream of copy paper that is 11” L x 8 ½” W x 2” H. To determine the correct film width, we will only look at width and height. We’ll use the length later on. Back to our ream of copy paper. If it measures 8 ½” W and 2”H, the calculation looks like this:
(8.5 + 2) + 2 = 12.5”
Since stock centerfolded shrink film rolls aren’t sold in fractional sizes and are stocked in even number widths, we will round up to 14”. To wrap your stack of 4 ½” W x 3” H brochures, you’ll need 14” Centerfolded Shrink Film. Next, you’ll need to know what gauge (thickness) your shrink film should be.
4 What Gauge Shrink Film Should I Use
Shrink film is very thin. How thin?
1 Mil = One thousandth of an inch (.001”)
1 gauge = One hundredth of a Mil
45 gauge = .00045”
Shrink film is also very strong. You know this because you’ve tried so hard to open a shrink wrapped package that you had to resort to using a knife, scissors or your teeth (?!!).
The standard thickness for PVC is 75 gauge. 100 gauge is also common. Either way, PVC shrink film isn’t recommended for sharp, pointy or heavy products.
75 gauge – printed products, CD/DVD, toys, non-food products
Polyolefin comes in a wide range of stock thicknesses. The most common are 45, 60, 75 and 100.
45 gauge – lightweight products or for use as a simple dust-cover
60 gauge – bakeries, stationery, printed materials, etc.
75 gauge – good for just about anything, even products weighing upwards of 35 lbs
100 gauge – very heavy products or items with very sharp/jagged edges
5 How Many Rolls of Shrink Film Will I need
Earlier we said we’d get to package length and finally we are here. Knowing the length of your package will help you determine how many rolls of film you’ll need to finish a job. The formula to determine how many packages a roll of shrink film will produce is:
(Roll Length in Feet x 12) ¸
Every roll of shrink film has a guaranteed number of feet. The higher the gauge, the less feet on a roll. Some common put-ups (roll footages) are:
75 gauge – 2,000’ per roll
100 gauge – 1,500’ per roll
45 gauge – 5,830’ per roll
60 gauge – 4,370’ per roll
75 gauge – 3,500’ per roll
100 gauge – 2,625’ per roll
If your product is 7” long and you are going to use 60 gauge film, you’d get this many packages per roll:
(4,370’ x 12) = 52,440’ of film per roll
(11” L + 2” H) + 2 = 15” of film per package
In real life, you won’t get exactly 3,496 wrapped reams of paper from one roll of 60 gauge shrink film. This is because each package won’t use precisely 15” of film. The real measurement will vary a bit. Also, you need to consider waste. You will waste some film setting up the l-sealer and tunnel. You will also have some packages along the way that need to be re-wrapped. We typically use a 1% waste factor. You probably won’t actually waste that much film but, by being conservative, you’re much more likely to not run out of film during your production run:
3,496 * 1% waste factor = 3,461 packages per roll (real world)
6 How much will it cost to wrap each package?
That’s the easiest of all questions to answer. Here’s how to calculate your packaging cost:
Cost per Roll ¸ Number of Packages per Roll = Approximate Cost Per Package
Using our ream of paper and 14” 60 gauge centerfolded shrink film at an average roll cost of $175:
$175 cost per roll ¸ 3,461 packages per roll - $0.050 cost per package
7 The Wrap-Up
Now you know how to:
·Calculate shrink film roll width
·Pick the right gauge shrink film
·Calculate how many rolls of film you will need
·Determine your cost per package
If you are unsure about roll width or recommended film thickness (gauge), we have packaging experts ready and waiting to help. Contact one of them by email or call toll free 855-373-7225 (855-DPD-Pack).