This is the third and final post about different paper types and paper grades. This post is to highlight some characteristics used to classify paper. Be sure to click on the links above to view our previous posts about this subject.
Most paper characteristic methods are established by The American Society for Testing and Materials or the Technical Association of the Pulp and Paper industry. These two organizations are and the forefront of establishing methods and characteristics of a variety of paper types. We will only be going over a few characteristics and testing that is used. There is a large variety that is used to classify paper.
Moisture Content- Paper is tested by oven-drying and a value is expressed on an oven-dry basis.
Thickness of Paper- There are a variety of readings that must be used to establish paper thickness. The paper is compressed repeatedly and measured using a micrometer. After several readings a caliber is assigned to the paper.
Brightness- A common characteristic many people even look for in print paper. Brightness is measured in spectral reflectance. On most print paper the brightness is express from 1-100 with 100 being the brightest paper.
Gloss- Another common characteristic that people buying print paper are aware of. The gloss of paper is measured using specular gloss. The specular gloss method is also used for determining “high” gloss down to “low” gloss.
Opacity- A very important measurement characteristic when printing on paper. Opacity helps to identify if ink will show through on the reverse face when printed on.
Grease Resistance– A great measurement when the paper will be coming into contact with grease. This is a turpentine test used to measure the amount of grease resistance the paper has. Poly coated Kraft paper is a perfect example of paper that would be important to know the amount of grease resistance.
Stiffness– a stiffness test is important for a variety of paperboard types. Maintaining stiffness in paperboard is important for use in a variety of products such as paperboard box displays. This stiffness helps to establish the amount of strength the paper board has. The Clark stiffness test is commonly used for lightweight paperboard testing and the Taber stiffness is often used for heavier paperboard testing.
Tensile Strength- A common measurement to measure the paper strength in tension. Tensile strength is measured using a pendulum instrument to determine the force per width to break a specimen.
These are only a handful of the paper testing characterizations used to determine paper type and grade. These paper testing methods help manufactures, producers, and consumers become knowledgeable on which products to use for specific applications.