Hope, you have been waiting to get the continued part of this blog.

In the previous blog we have read about the importance of testing corrugated boxes and the best testing procedures that we can use to test the strength and multiple properties of packaging corrugated boxes. In our last blog, we have mentioned that there are multiple tests we can run on corrugated boxes to check their compatibility with different applications. These are:

• Bursting Strength Test
• Edge Crush Test
• Cobb Sizing Test
• Vibration Test for Packaging
• Box Compression Tester
• Grammage Test

We have already covered the Bursting Strength Test and Edge Crush Test in the last blog, let’s now talk about a few more here.

Third test that you can perform to test the strength of corrugated / double-ply / tri-ply / 5-ply sheets is the Cobb Sizing test.

• Cobb Sizing Tester

About: To know the water resistance strength of the corrugated boards when exposed directly to water.
Purpose: To test the porosity of the corrugated boxes.

Corrugated boards are made of heavy paper sheets. These sheets or boards are thick in nature and have capacity to absorb water and retain it for a while when subjected to water. The cobb sizing tester is a testing machine which is used to measure how much amount of water the board can absorb.

How to perform this test?
In this test procedure, first-of-all, the sample is subjected to water. Then, water is squeezed out of the sample by exerting pressure onto it using a heavy steel roller. Depending upon the quality of the board, the water cannot be squeezed completely out of it. This helps us in finding the Cobb Value of the corrugated board.

Formula to calculate the cobb value is,

Cobb Value = Weight of the sample before testing - Weight of the sample after testing

How does cobb value help to measure the quality of the cardboards?
The lower the Cobb value, the more will be the water resistance strength of the corrugated board.

The cobb test is mandatory to perform for certain applications especially where a few hazardous materials are packed inside the corrugated boxes.

Next is,

• Paper Grammage & Thickness Test

About : Measure the density & thickness of a board
Purpose : To test box quality and rigidity

The fundamental properties of a paper or a paper board is its thickness and grammage. These properties determined the quality of a corrugated box. You might be wondering what is the “ideal” grammage or the thickness of a sheet of paper.
Well…

As per the standards, there is no ideal grammage or thickness mentioned in any book. You can choose the weight, thickness and grammage of the sample as per the requirement of your application.

For example, when you need more padding to safeguard any fragile products, you can easily choose a board with higher thickness or weight. The thick boards have larger flutes that can pack more air inside them whereas the thin boards have dense flutes with high grammage. You can use thin board corrugated boxes for compact packaging.

Thickness is usually measured in mm (millimetres)
Grammage is expressed in g/m2 (grams per meter square)

When more padding is required, a box with a higher thickness can be used. Thick boards are usually sturdy & appropriate for heavy-duty shipping as they have large flutes that pack more amount of air. You can find cardboards with different flute sizes in the market. These sizes are called A, B, C, E, or F, where the cardboard with C flute size is the most common one i.e. 4.0mm.

On the other hand, thin boards have thin flutes in them which means they have high grammage. Such boxes are used when the packaging needs to be more compact and rigid. Thinner boards are easy to fold, light-in-weight and more suitable when it comes to printing or detailing.

For more information on the above mentioned tests, you can reach our team of experts at Pacorr Testing Instruments and get the solution of your queries.

Hope you have gained a lot more information about corrugated boxes in this blog.

Keep following us, we will come up with a few more testing techniques in the third part of the blog. Stay Tuned!

Part-3