CMC Tolerancing

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CMC 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.

The CMC calculation mathematically defines an ellipsoid around the standard colour with semi-axis corresponding to hue, chroma and lightness. The ellipsoid represents the volume of acceptable colour and automatically varies in size and shape depending on the position of the colour in colour space.

The ellipsoids in the orange area of colour space are longer and narrower than the broader and rounder ones in the green area. The size and shape of the ellipsoids also change as the colour varies in chroma and/or lightness.

The CMC equation allows you to vary the overall size of the ellipsoid to better match what is visually acceptable. By varying the commercial factor (cf), the ellipsoid can be made as large or small as necessary to match visual assessment. The cf value is the tolerance, which means that if cf=1.0, then Delta E CMC less than 1.0 would pass, but more than 1.0 would fail.

Since the eye will generally accept larger differences in lightness (l) than in chroma (c), a default ratio for (l:c) is 2:1. A 2:1 ratio will allow twice as much difference in lightness as in chroma. The CMC equation allows this ratio to be adjusted to achieve better agreement with visual assessment.

Applications

  • Chemicals
  • Coatings
  • Food and Beverage
  • Household Products
  • Plastics
  • Textiles
Title Application Part Number Mark as favourite
Extremely portable Spectrocolorimeter, perfect for quick and accurate colour measurement
  • Chemicals | Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Pharmaceuticals and Cosmetics | Plastics | Sugar Solutions, Syrups and Honey | Textiles
401100
Hand-held spectrocolorimeter offering quick and accurate colour measurement with the added benefit of a portable viewing stand
  • Chemicals | Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Pharmaceuticals and Cosmetics | Plastics | Sugar Solutions, Syrups and Honey | Textiles
401120
Our non-contact spectrophotometer enables colour measurement of powders, gels, liquids, creams and pastes from a distance, in their natural state
  • Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Plastics | Sugar Solutions, Syrups and Honey | Textiles | Waste Water Treatment
400810
Entry-level colour quality control package which works with many of the Lovibond® spectrophotometers
  • Chemicals | Coatings | Household Products | Plastics | Textiles
400590
comprehensive colour quality control package avilable for all Lovibond® spectrophotometers from handheld to benchtop units
  • Chemicals | Coatings | Household Products | Plastics | Textiles
400610
RT 250 Spectrophotometer is ideal for the measurement of materials such as paper, plastic, fabric and a variety of hard surfaces
  • Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Plastics
402505
This portable hand-held spectrophotometer allows you to obtain absolute and differential measurements in the lab, plant or field
  • Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Plastics
400300
This portable handheld spectrophotometer is the most convenient way to measure colour, allowing you to obtain accurate measurements in the lab, plant or field
  • Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Plastics
400305
This portable handheld spectrophotometer is the most convenient way to measure colour, allowing you to obtain accurate measurements in the lab, plant or field
  • Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Plastics
400310
Highly flexible and portable spectrophotometer provides the perfect opportunity to measure colour anywhere in your facilities
  • Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Plastics
400320
This cost effective, portable and flexible spectrophotometer featuring sphere technology is perfect for measuring colour on site or in the field
  • Chemicals | Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Pharmaceuticals and Cosmetics | Plastics | Textiles
400400
Portable sphere spectrophotometer with extreme flexibility for multiple applications. An ideal mid-range solution for accurate colour measurement
  • Chemicals | Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Pharmaceuticals and Cosmetics | Plastics | Textiles
400500
Portable sphere spectrophotometer with extreme flexibility for multiple applications. An ideal mid-range solution for accurate colour measurement
  • Chemicals | Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Pharmaceuticals and Cosmetics | Plastics | Textiles
400505
Portable sphere spectrophotometer with extreme flexibility for multiple applications
  • Chemicals | Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Pharmaceuticals and Cosmetics | Plastics | Textiles
400504
Flexible sphere spectrophotometer with switchable 4mm & 8mm aperture. Lightweight and portable, perfect for your colour measurement needs
  • Chemicals | Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Pharmaceuticals and Cosmetics | Plastics | Textiles
400520
Sphere spectrophotometer for larger areas with 14mm aperture. Lightweight and portable, perfect for your colour measurement needs
  • Chemicals | Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Pharmaceuticals and Cosmetics | Plastics | Textiles
400530
Reliable and accurate compact benchtop spectrophotometer ideal for small to medium-sized manufacturers looking to establish accurate colour measurement
  • Chemicals | Coatings | Food and Beverage | Household Products | Medical and Clinical Products | Pharmaceuticals and Cosmetics | Plastics | Textiles
407000
Reliable and accurate compact benchtop spectrophotometer ideal for small to medium-sized manufacturers looking to establish accurate colour measurement
  • Chemicals | Coatings | Food and Beverage | Household Products | Plastics | Textiles
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