At the end of this module, you will be able to:
- List common criteria used to differentiate between paper and board grades
- List some common paper and board grades
- Describe basis weight testing, including principles and units
- Describe moisture testing, including principles and units
- Describe caliper, density and bulk testing, including principles and units
- Describe smoothness testing, including principles and units
- Describe porosity testing, including principles and units
- Identify the organizations which have established standard testing, sampling, and conditioning procedures
- Explain how sheet formation and moisture content can affect test results
- Describe the importance of standardized sampling techniques and sample conditioning
The following key questions are answered in this module:
Which standardized test methods are most commonly used in the U.S.?
The standards managed by the Technical Association of the Pulp and Paper Industry (TAPPI) are most common.
What is basis weight?
Basis weight refers to the weight in pounds of a ream of paper, where a ream is defined as 500 base size sheets. Different grades have different base sizes so basis weight cannot be directly compared across grades. Grammage (grams per square meter) is another way to express the weight per area, and values can be directly compared.
What is caliper?
Caliper is the thickness measurement of paper or board.
How is smoothness measured?
There are many different ways to measure smoothness (optical, friction, profile measurements, ink contact area) but air flow measurements are must commonly used.
Why is porosity measured?
Porosity determines the ability of a sheet to absorb ink or water, protect certain products, or act as a filter.
Below is a transcript of the video sample provided for this module:
Porosity is a measure of the air resistance or air permeability of a sheet. This property effects the ability of a sheet to package and protect certain products, to absorb liquids like water and ink, or to act as a filter. Various instruments have been developed and are used, and most of them work in one of two ways. They either measure the length of time it takes for a specific volume of air at a controlled pressure to pass through a defined area the sheet. Or they measure the air flow rate through an area of the sheet while maintaining a constant pressure difference.
Use the additional resources and links below to learn more about this topic: