The organic and inorganic chemicals used in the manufacture of many products are not only required to be of a specified purity but frequently need to be of a particular colour value.

Discoloured chemicals in industry will adversely affect the appearance of the finished product and in turn will create doubt in the mind of the end user as to its quality.

This applies to liquids, solids, powders and slurries.

Please do not hesitate to contact us to discuss your specific application.

Scales & Values

Grading techniques are widely used to assess product colour by comparison with a representative series of fixed colour standards.

For many product types, a characteristic set of standards was agreed and adopted to aid colour control and the communication of coloour specifications; the result is s selection of traditional colour grading scales that have been adopted as industry standards and are still common today.

Your colour scale determines your instrument choice. We would be delighted to offer advice as to the correct colour scale and thus instrument choice for your application. Please do not hesitate to contact us.

Colour Scales:

  • Acid Wash Test (ASTM D848)
    • This colorimetric test refers to refined products of coal tar consisting esentially of hydrocarbons boiling below 200°C and substantially free from phenols and pyridine bases
    • It is designed to give an indication of impurities found in Industrial Aromatic Hydrocarbons which, if sulphonated, would cause the material to be discoloured. These materials include benzene, toluene, xylenes, refined solvent napthas and other similar industrial hydrocarbons
    • Instruments that can be used: PFX880 / CIE / Heated; PFX/i-195/C or PFX/i-195/9
  • Anti-Icing in Aviation Fuels
    • The prevention of fuel system icing in some aircraft depends on the presence of an anti-icing additive in the fuel
    • The additive now commonly used is diethylene glycol monomethyl ether (DiEGME)
    • For complete protection, it is necessary for the quantity of DiEGME to exceed a certain minimum level when the fuel enters the aircraft
    • It is therefore necessary to check the DiEGME content of the fuel at various points between the blending stage and the aircraft fuel tanks
    • Instruments required: Lovibond® Comparator; daylight unit, disc 4/33, 13.5 mm cells
  • CIE 94
    • In 1994 the CIE released a new tolerance method called CIE94. Like CMC, the CIE94 tolerancing method also produces an ellipsoid. The user has control of the lightness (kL) to chroma (KC) ratio, as well as the commercial factor (cf). These settings affect the size and shape of the ellipsoid in a manner similar to how the l:c and cf settings affect CMC.
    • However, while CMC is targeted for use in the textile industry, CIE94 is targeted for use in the paint and coatings industry. You should consider the type of surface being measured when choosing between these two tolerances. If the surface is textured or irregular, CMC may be the best fit. If the surface is smooth and regular CIE94 may be the best choice.
    • Instruments that can be used: RT range / OnColor range
  • CIE L*u*v* Colour Space
    • uniform colour space adopted in 1976. Appropriate for use in additive mixing of light. (eg., Colour Television)
    • Instruments that can be used: RT range / OnColor range; NC45
  • CIE L*a*b*
    • A Colour space in which values L*, a* and b* are plotted using a Cartesian coordinate system. Equal distances in the space approximately represent equal colour differences. L* represents lightness; a* represents the red/green axis; and b* represents the yellow/blue axis. CIE L*a*b* is a popular colour space for measuring both reflective and transmissive samples.
    • Instruments that can be used: most instruments in the Lovibond® range
  • CIELAB (L*C*h)
    • This is an assessment of colour system that is more usually used to set tolerances once the hue, chroma and lightness limits are established.
    • While CIELAB (L*a*b*) uses Cartesian coordinates to calculate a colour in a colour space, CIELAB (L*C*h) uses polar coordinates. This colour expression can be derived from CIELAB (L*a*b*). The L*, as before defines lightness, C* specifies chroma and h denotes hue angle, an angular measurement.
    • The L*C*h expression offers an advantage over L*a*b* in that it is very easy to relate to the earlier systems based on physical samples, like the Munsell Colour Scale.
    • Instruments that can be used: most instruments in the Lovibond® colour range
  • CMC Tolerancing
    • MC is not a colour space but rather a tolerancing system.
    • CMC tolerancing is based on CIELAB (L*C*h) and provides better agreement between visual assessment and measured colour difference. CMC tolerancing was developed by the Colour Measurement Committee of the Society of Dyers and Colourists in Great Britain and became public domain in 1988.
    • Instruments that can be used: RT range / OnColor range; NC45
  • Delta E* colour difference
    • Assessment of colour is more than a numeric expression. Usually it’s an assessment of the colour difference (delta) from a known standard. CIELAB (L*a*b*) and CIELAB (L*C*h) are used to compare the colours of two objects.
    • The expressions for these colour differences are DL*, Da*, Db*, or DL* DC* DH* ("D" symbolises "delta," which indicates difference). Note: DH* is usually used instead of Dh to enable DE* to be calculated.
  • Gardener Colour ASTM D 1544
    • A single number, one dimensional, colour scale for grading the colour of similarly coloured liquids such as resins, varnishes, lacquers, drying oils, fatty acids, lecithin’s, sunflower oil and linseed oil.
    • The scale ranges from a pale yellow to a red in shade and is described in terms of the values 1-18. The glass standards used with the comparator can achieve a resolution of 1 unit, automatic PFX and PFXi instruments 0.1.
    • Instruments that can be used: AF334; instruments in the PFX range
    Hunter Lab
    • A uniform color scale devised by Hunter in 1958 for use in a color difference meter. It is based on Hering’s opponent-colors theory of vision.
    • Instruments that can be used: RT range / OnColor range; NC45
  • Lovibond® RYBN Colour
    • 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, chemicals, pharmaceuticals and syrups.
    • Instruments that can be used: PFX range
  • Optical density (Absorbance)
    • Please note; with both our PFX and PFXi ranges Absorbance is referred to as Optical Density (OD). This is an available Colour Scale.
    • Absorbance should not be confused with Absorptance (the fraction of light absorbed by a sample.)
    • Instruments that can be used: PFX range
  • Spectral data
    • Spectral data, where colour measurement is concerned, is the data derived from measuring the level of reflectance or transmittance of a given colour at selected wavelengths throughout the visible spectrum.
    • Instruments that can be used: PFX and RT range
  • Transmittance
    • The ratio of transmitted flux to incident flux under specified conditions
    • Instruments that can be used: PFX range
  • xyY chromacity co-ordinates
    • The coordinates x, y, and z are derived from the XYZ Tristimulus values by the following calculation such that x + y + z = 1, x = X/(X + Y + Z), y = Y/(X + Y + Z), z = Z/(X + Y + Z)
    • The values of x and y can then be used to pinpoint a colour in the x y coordinate system. The x and y chromaticity coordinates are generally reported along with the value of luminance factor Y
    • Instruments that can be used: most instruments in the Lovibond® colour range
  • XYZ tristimulus values
    • The CIE XYZ 1931 Tristimulus system is a modified version of the RGB colour tristimulus system and uses non real or imaginary stimuli. This innovation allows all colours within its gamut to be expressed as positive numbers, unlike the RGB system, where some colours fall outside its gamut and are expressed as negatives. The XYZ chromaticity co-ordinates are defined as x,y,and z
    • Instruments that can be used: most instruments in the Lovibond® colour range
  • Yellowness Index (ASTM E 313)
    • Yellowness Index is a number calculated from spectrophotometric data that describes the change in colour of a test sample from colourless through to yellow
    • The American Standards Test Methods (ASTM) has defined whiteness and yellowness indices. The ASTM’s E313 yellowness index is used to determine the degree to which a sample’s colour shifts away from an ideal white. The D1925 yellowness index is used for measuring plastics
  • Platinum-Cobalt / Hazen / APHA Colour (ASTM D 1209)
    • Often referred to as Pt-Co, Platinum-Cobalt, Hazen or APHA Colour. All terms are interchangeable and equally valid
    • Used to measure clear to dark amber liquids
    • Used extensively in the water industry but also for clear oils, chemicals and petrochemicals such as glycerine, plasticisers, solvents, carbon tetrachloride and petroleum spirits
    • Instruments that can be used:
      • AF329, 0 – 250 mg Pt/l, discs (CAA, 0 – 30 mg Pt/l; CAB, 30 – 70 mg Pt/l; NSB, 70 – 250 mg Pt/l
      • AF325, 10 – 250 mg Pt/l, discs (NSH, 10 – 90 mg Pt/l; NSB, 70 – 250 mg Pt/l)
      • AF328, Low Range, 0 – 70 mg Pt/l, discs (CAA, 0 – 30 mg Pt/l; CAB, 30 – 70 mg Pt/l)
      • AF327, Low Range, 0 – 70 mg Pt/l, discs (1209/1, 0 – 30 mg Pt/l; 1209/2, 30 – 70 mg Pt/l)

Additional information

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