Standard Laboratory Conditioning Protocols for Coated Folding Boxboard Evaluation
Valid boxboard physical testing requires ISO 187 conditioning at 23°C and 50% RH to prevent hysteresis errors in stiffness, yield, and creasing metrics.
ISO 3783
Testing Protocol
The international standard that specifies the method for determining the resistance of paper and board to picking using the accelerating speed method is essential for print quality control. Known as iso 3783, this testing method simulates the rapid separation force between ink and the paper surface that occurs on high-speed printing presses. The result provides a numerical value that determines whether the paper can withstand tacky inks without surface damage.
Mechanical Method
A specialized testing instrument applies a high-viscosity oil or ink to the sample sheet under escalating speed. As the test wheel accelerates, the tension on the surface coating increases until the fibers or pigments begin to rupture. This point of failure is marked by the start of picking, where the coating is lifted from the base sheet.
The velocity at which this damage occurs is recorded as the pick velocity, providing a measurement of the surface strength of the material. This procedure must be conducted under controlled laboratory temperature and humidity, as temperature changes alter the viscosity of the oil used in the test.
Surface Assessment
Laboratory operators analyze the tested strip under magnification to pinpoint the exact location of the first rupture. If the pick occurs at a low velocity, the paper is unsuitable for high-speed offset printing where tacky inks are used. Achieving a high rating under the iso 3783 standard ensures that the paperboard can run on high-speed presses without creating dust or lint that would contaminate the printing plates and cause defects.