Get Your Colour Story Right – With the Right Scale

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Introduction
Importance of knowing the right scale
Lovibond® RYBN Scale
Lovibond® RY Scale
Lovibond® RY 10:1 Scale
AOCS-Tintometer® Scale
Gardener Scale
Factors affecting colour readings
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Measurement Decisions


There are four key decisions that must be made prior to measuring colour in oil consistently:

1) The choice of colour scale to be used in communicating the colour data.
2) Visual versus automatic measurement.
3) The path length across which the colour will be measured.
4) Possible dilution of the sample

It sometimes happens that people find themselves trying to compare results that were not measured in the same colour space. Over the years, there have been several different methods derived from Lovibond® RYBN that give results in red and yellow units. If a specification does not clearly define which of these versions is being used, confusion may (and often does) arise. Different methods and scales will give different results.

Choice of Scale
The purpose of colour scales is to replicate the range of colours unique to a particular application or sample. There are a number of scales which are used for measuring
edible oil colour. Your supplier or customer will be working to an existing scale, and it is important to try and maintain colour communication within a single scale


Comparing colour values across different measurement scales—such as Lovibond® RYBN (Visual vs. Automatic), AF960 RY, and AOCS-Tintometer®—without knowing the exact definition of red, yellow, blue, and neutral units in each scale is like comparing temperatures in Fahrenheit and Celsius without converting between them. The numbers may look similar, but they represent fundamentally different scales.

This lack of clarity can lead to:

  • Quality control issues
  • Miscommunication with suppliers or customers
  • Incorrect batch rejections or release

Lovibond® RYBN Colour Scale

The Lovibond® Scale is based on 84 calibrated glass colour standards of different densities of magenta (red), yellow, blue and neutral, graduating from desaturated to fully saturated. Sample colours are matched by a suitable combination of the three primary colours together with neutral filters, resulting in a set of Lovibond® RYBN units that define the colour. Since several million combinations are available, it is possible to match the colour of almost any sample; it is particularly popular for measuring the colour of oils and fats. Designed originally for visual colour assessment, this scale has been since digitised This method can now be expressed using automatic equipment. Lovibond® RYBN uses a combined numbering system to represent values for the following colours: • Red • Yellow • Blue • Neutral

To ensure consistency, accuracy, and confidence in colour assessment, especially in applications like edible oil quality.

The Lovibond® RYBN scale is the most recommended and reliable standard. It offers a clearly defined, globally recognized method that aligns visual and automatic measurements, helping eliminate errors and ensuring precise colour communication across the supply chain.

 

The Lovibond® RYBN colour scale is the preferred colour scale when measuring Lovibond® colour as it most closely correlates with the way in which visual instruments are designed to be used. There are the two working practices which are sometimes used in visual systems, to simplify the comparison of samples with glass colour standards.

Explore the Lovibond® RYBN Colour Scale!

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Lovibond® RY

Uses only the Red and Yellow glass standards when comparing two samples (or sample with a standard). This will often lead to lower values in the reported match due to the brightness difference in visual measurement systems. A higher variation between users will be seen, as a more subjective decision on the match at different brightness levels is being made.

An RY result may be correct, but often a complete result requires Neutral values as well.

Lovibond® RY 10:1

In some sample oils, there is a useful relationship between Yellow and Red colour values (where Yellow is approximately ten times the Red value). The 10:1 ratio is often a useful point to start from when making a colour match, then improved to a more precise match using the full gamut of Red, Yellow, Blue and Neutral. 

The RY 10:1 ratio is a step in the process of achieving a good RYBN match, but it is not a final result.

American Oil Chemists Society (AOCS) AOCS-Tintometer® Scale

• AOCS Cc 13b-45, Colour of Fats and Oils, Lovibond® (Wesson) Wesson Method Using Colour Glasses Calibrated in accordance with the AOCS-Tintometer® Colour scale • AOCS Cc 8d-55, Refined and Bleached Colour in Tallow and Greases Intended for Soap Production • AOCS Cc 13j-97, Colour of Fats and Oils, Automated Method The AOCS-Tintometer® colour scale is a scale of Red and Yellow colour values only The scale differs in its values from the Lovibond® RYBN scale so measurements between the two scales are not comparable. The AOCS-Tintometer® scale also uses a different viewing system for visual measurement: in the Lovibond® RYBN method the sample and coloured glass are side by side while in AOCS-Tintometer®, the sample and coloured glass are shown in separate circles of colour. 

Gardner Colour Scale

The Gardner scale is used to evaluate light to dark yellow oils, especially in industrial or specialty oils. It assigns a single number value from 1 (light) to 18 (dark).

Common applications include Castor oil, Linseed oil, etc.

The usage of the Gardner scale is less recommended as it is a linear scale, unlike the Lovibond® scale, which is logarithmic.  

Learn more about the Lovibond® Logarithmic scale! 

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Curious about what affects the colour readings of your edible oil samples? Explore the key influencing factors!

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Need help choosing the right scale or instruments for your edible oil testing?