…if you had an enjoyable holiday weekend.  I sure did.  This week’s topic is cardboard, compression, and crush tests.

There are three types of cardboard box:  single wall, double wall, and triple wall.  The more walls, the stronger the box.  The heavier the item to be shipped, the stronger the box needed to ship it in.  So, how do you know if you need a single, double, or triple walled box?  The answer lies in the answers of three questions:  How heavy is the item?  How valuable is the item?  How big is the item?

First, let’s talk about how to gauge the quality of the cardboard box you use.  On the bottom of the box, the manufacturer places a stamp that is usually round or rectangular.  This stamp is called a “Box Manufacturer’s Certificate.”  You’ll find important information detailed within the certificate.  For example, the manufacturer will indicate if the box has a single, double, or triple wall.  If no certificate is available, you can count the layers of flutes to determine what kind of box you have.  A single wall box has only one layer of flute enclosed by a liner on each side, a double wall box has two flutes, and a triple wall box has three flutes.  Each flute layer will be separated by a liner.  Next, you’ll see a series of numbers recorded in the Box Manufacturer’s Certificate.  Some manufacturers will provide a number called “burst strength.”  This number indicates the amount of force needed to rupture the box walls.  The higher the burst strength number, the sturdier the box.  Other manufacturers will display a number called an ECT or Edge Crush Test number.  Again, the higher the number, the sturdier the box.  As a rule, you want to use a box that has no less than a burst strength of 200 pounds per square inch.  If you have a choice, go for the box that shows burst strength instead of edge crush test strength.  Burst strength is a better indicator of how well the items inside the box will be contained intact because it’s a measure of how the wall of the box is constructed.  ECT indicates how well the box will hold up if stacked one on top of another, or in other words, how well the box will resist being compressed by other laden boxes.  If you are really motivated to dive deeper into the physics and mechanics of how cardboard boxes are created, here are three links to sites where you can get into the details:

http://www.parcelindustry.com/ME2/Audiences/dirmod.asp?sid=&nm=&type=Publishing&mod=Publications%3A%3AArticle&mid=8F3A7027421841978F18BE895F87F791&tier=4&id=A0303D3EB0C7413F86881A4AA184C99F&AudID=B2C%20Express

http://www.unitload.vt.edu/technote/980918/980918.htm

http://www.richbox.com/about_boxes/box_performance.asp

Another important number included in the Box Manufacturer’s Certificate is the amount of weight that can be loaded safely within the box.  Never put more weight in a box that it can handle. 

Getting back to the three questions we started with (how heavy, how valuable, how big), a single wall box will suffice for almost anything you want to ship.  A double wall box is good for heavy items, but two single wall boxes can do the job if a double wall box isn’t available.  When it comes to triple wall boxes, you’re probably dealing with something that should be shipped as freight and should consider having the item shipped within a crate to ensure security and stability.  For me, the item’s weight drives the decision to double-box or to use a double wall box.  Just last week, I used a double wall box to package an item that weighed 60 pounds.  It made better sense to do that than to double box it.  Each item is unique, and there is variation in what packaging experts would agree is acceptable.  My rule of thumb is, if the item arrives at its destination unscathed and intact, then the packaging was right!

Sometimes, it’s prudent to double box an item that is not particularly heavy but that is highly valuable and/or fragile.  I’ll talk about when to double box in next week’s installment.