Grammage Test
The mass of one square metre of paper or corrugated board, weighed on a precision balance under standard laboratory conditioning (23 °C, 50% relative humidity). Unit: g/m².
Unit g/m²
Quality
Our quality policy
At Korupak, international quality standards guide every production process, from raw material to finished product:
- 01
To meet our customers' industry needs and expectations at the highest level, with sound engineering and optimal cost.
- 02
To deliver consistent, sustainable quality by testing paper, adhesive, board and box at every stage in our advanced quality control laboratory.
- 03
To follow technological developments closely and keep a culture of continuous improvement (Kaizen) alive in all our processes.
- 04
To build shared quality awareness with all stakeholders, from suppliers to employees, and to produce in an environmentally responsible, recyclable way.
Laboratory tests
Paper (raw material) and process control tests
RCT
Ring Crush Test
A strip of paper is formed into a ring and loaded along its vertical axis to find the maximum compressive force it can carry before it buckles or crushes. It directly affects the stacking strength of the box. Unit: kN/m.
Unit kN/m
CMT
Concora Medium Test
Fluting paper is corrugated in the lab at 175 °C, then loaded at right angles to its surface to measure its crush resistance. It shows how sound the flute structure is. Unit: newton (N).
Unit N
COBB
Water Absorption Test
The amount of water absorbed by one square metre of conditioned paper under a set water column within a defined time (usually 60 seconds). It shows how well the packaging resists moisture. Unit: g/m².
Unit g/m²
Corrugated board and box strength tests
ECT
Edge Crush Test
Force is applied to a corrugated board sample parallel to its flutes (vertically) to find the maximum load before it crushes. It is the key parameter for the vertical load capacity of a box. Unit: kN/m.
Unit kN/m
BCT
Box Compression Test
Gradually increasing vertical pressure is applied to a finished, empty corrugated box to find the maximum load it can carry without collapsing. It shows stacking performance in storage and shipping. Unit: kgf or N.
Unit kgf / N
FCT
Flat Crush Test
Pressure is applied at right angles to the board surface to measure the force needed to flatten the inner flutes completely. It describes the board's cushioning against knocks on production and filling lines. Unit: kPa.
Unit kPa
BST
Bursting Strength Test
The maximum hydraulic pressure, applied through a circular elastic diaphragm, that a corrugated board or paper sample withstands before it bursts. It shows resistance to local stress and puncture from inside and outside. Unit: kPa (or kgf/cm²).
Unit kPa
Physical, chemical and optical control tests
Thickness (Caliper)
The thickness of raw paper and finished corrugated board under standard pressure, measured with a precision digital micrometer. It confirms that the flutes were not crushed during production or printing. Unit: mm.
Unit mm
Moisture Test
Measures the moisture content of paper reels and finished corrugated sheets. The right moisture balance is critical for bonding quality and for keeping the box's BCT strength. Expressed as a percentage.
Unit %
Viscosity (Adhesive Quality Control)
Measures the flow resistance and consistency of the starch-based (Stein-Hall) adhesive that bonds the corrugated layers. It is checked continuously for clean fibre tear and strong bonding. Measured in seconds (Stein-Hall cup) or cP (Brookfield).
Unit s / cP
Spectrophotometer (Colour Measurement)
Optical spectrum analysis checks that the ink shades on printed boxes match customer references and Pantone standards. It keeps colour accuracy (Delta E) consistent in every production batch.
Unit ΔE
Certificates
A quality journey, certified
Having started its quality journey by applying the principles of quality management, and guided by them ever since, KORUPAK has made it its principle to give customers high-quality, safe and continuous service.
- 2012FSC®Licence
- 2015IQRQuality management certificate
- 2018FSC®Certificate
Let's design your box together
Contact our sales team for the best packaging design for your products and technical support.