color measurement in coil coating

Why is it color measurement so important in production?

color is a primary quality criterion. If color a product is not the same on different surfaces, everyone immediately sees the difference. We use the visual impression to decide within seconds whether we like the product.

A color measurement in the laboratory is important, but provides the information too late to intervene in the running process in case of color variations. Inline color measurement helps the operator to control his production process so that in the end a consistently good quality is always delivered to the customer.

Consistent colour results through automated quality control

The special challenges of inline color measurement

Often the finished product is covered with a protective film during coil coating. Thus, the result can only be perceived after removing the film. But then it is too late. 

Complaints are now expensive and lead to a loss of image. For this reason, the coating must be measured during production. Only then can it be ensured that the mounted panels also correspond to the target. To do this, the ERX145 spectrophotometer is strip mounted on a traversing beam cross-axis. The measuring position is typically behind the water quench but in front of the output accumulator. The measurement results can be used to control the ink application reliably. The employees in the ink kitchen can also prepare the inks based on these color measurements.

However, as it strip is still hot at this point, temperature compensation is recommended. On the coating machine not only the color, but also the temperature is measured. With a procedure specially developed by X-Rite, the measured color values can now be calculated back to room temperature (thermochromic compensation). Thus the inline measured colour values are independent of the temperature of the material. The inline color measurement correlates perfectly with the laboratory.

Consistent colour results through automated quality control

  • With the inline color measurement and evaluation of color deviations, the entire production process can be recorded without interruption.
  • The color measuring system works with a network connection or an OPC interface to receive data from the superordinate system. Thus a new job is started automatically. The measured values can also be transmitted to a quality control system.
  • Measurement of a wide variety of surfaces, such as glossy or matt, but also grained and embossed structures can be reliably detected.
  • The color measuring instruments work in the harsh production environment, absolutely independent of ambient light influences.
  • The non-contact operation protects the material to be measured.
  • Graphic displays and acoustic alarm indicate when tolerances are exceeded.
  • This results in a complete documentation of the color measurement results, which is also available for later evaluation.
  • Objective evaluation according to internationally recognized standards ensures the integrity of the inline measurement program.

Advantages at a glance


< 7 months

Response time

3 min

Color correlation to the laboratory





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The ERX145 - 45°a:0° measurement directly on the machine

The ERX145 system is optimized for the color measurement coil coating industry and can eliminate costly errors on the production line. The automatic quality control captures the color coated strip without touching it and displays it graphically. The system is easy to use and works on any material even in the most difficult production environments. That color of the current production is measured and compared with the stored target values, so that a change can be reacted to immediately and a uniformity colorof the coil can be ensured.

GlossFlash 6060 for inline gloss measurement

Parallel to thiscolor , shine often also plays an important role. With the GlossFlash 6060, gloss is measured at 60° and displayed parallel to the color values in the software. This measuring system is also designed for rough use on the production machine, measures contactlessly and is absolutely insensitive to ambient light. This gives the machine operator even more security to control his production process correctly.

Inline color and gloss measurement

➡ measures the temperature of the strip color independent of the strip temperature
➡ is also suitable for effect and structured surfaces
➡ helps to keep the color temperature on the coating machine constant
➡ gives machine operators security in production
➡ supports the color setting when starting a new color
➡ creates color consistency even with different production lots
➡ 100 % quality assurance of the entire production
➡ avoids rejects
➡ strengthens the reputation with customers
➡ pays for itself after a short time (typical ROI months!)


When you look at a facade on a building, directed optical conditions prevail:

The sun shines on the surface from a defined direction and we look at it from another direction.

These conditions are best simulated with the 45°:0° geometry. However, it is important that the illumination is circular (45°a:0°, the "a" stands for "anular"), otherwise differences to the laboratory can occur, especially with structured samples.

The ring illumination avoids shadows in the structures and is therefore insensitive to small changes in direction when the sample is inserted in the laboratory instrument.

Especially in the coil coating industry it is important to have a good correlation to the laboratory. This even goes so far that paint suppliers and coaters only talk about measured values and therefore do not exchange physical samples. Excellent instrument correlation is of course extremely important. 

The ERX145 is used both on the line as an inline unit and in the laboratory.

Thermochromic compensation is also carried out with the laboratory measuring instrument. This means that the colour values measured on the coating system are independent of the product temperature.

The system is supplied by X-Rite as a turnkey system. For this purpose, it is necessary to define the installation situation in the coating system and to determine it together with the customer's machine operators and technicians. The entire scope of delivery must also be discussed. Is it only a "simple" color measurement with traversing beam on the machine or should the system be able to do more. The following options are available:


  • color measurement on the front and back
  • Gloss measurement on the front and back
  • Measurement in the laboratory
  • Thermochromic compensation
  • Operation from the control station
  • Display of the colour values in the colour kitchen(s)
  • Connection to a process control system

Service technicians from X-Rite come to the installation and install the system into the machine within a few days. This requires a machine downtime of only a few hours. Of course, not only the operating personnel is trained in several shifts, but also the maintenance personnel and administrators.