ASBC Beer Color and Turbidity

ASBC Color

The ASBC Beer Color scale has a range of approximately 1 to 11 units, with the more yellow, pale worts at the low end of the scale and the redder color of dark worts, beers and caramels at the upper end of the scale.

The industry reference method for ASBC Beer Color and Turbidity Is:

ASBC Beer-10 Color of Beer Part A. Spectrophotometric Color Method available from ASBC – American Society of Brewing Chemists, affiliated with AACC – American Association of Cereal Chemists, St. Paul, MN USA Continue reading

Carbon Blackness [My], Jetness [Mc], Undertone [dM] and Tint Strength [T]

“Carbon black, also called charcoal black lamp black, pigment black, soot or black carbon, is a fine particle carbon pigment obtained as soot from the incomplete combustion of many different types of organic materials, such as natural gas, or oil. Carbon black is usually a fine, soft, black powder. It is very stable and unaffected by light, acids and alkalis. It is commonly used in printing and lithograph inks and in Chinese ink sticks. In industry, carbon black is used as a filtration material and a filler /pigment in coatings, rubber, plastics, paints, carbon paper, and crayons. Continue reading

What is Hunter Whiteness Index?

Hunter Whiteness Index [WIH]

There are at least half a dozen whiteness indices in use today, and a similar number of legacy whiteness indices no longer in use. There are subtleties among them and it is important to know the forms of these whiteness metrics and conditions for which they are derived for. In general, a material will exhibit high whiteness if the material reflectance has high and even reflectance, near 100%, across the visible spectrum.

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Do you have a source for EP Opalescence Standards?

The reference document that defines the visual EP Opalescence scale is:

EP 2.2 Physical and Physico-Chemical Methods for color and opalescence

EP – European Pharmacopoeia, Section 2.2 Physical and Physico-Chemical Methods, Unit European Pharmacopeia, Strasbourg, France (1997: 15-16)

This method describes the visual evaluation of scattering or opalescence in near clear liquids, typically pharmaceutical, relative to distilled water being a perfect clear.

There are two types of physical liquid standards for visual turbidity or opalescence – Formazin solution (with or without stabilizer) and polymer beads (polystyrene micro spheres). The Formazin solution is the historical liquid scattering standard but the polymer beads is considered more stable and homogenous.

Section 2.2.1 Clarity and Degree of Opalescence of Liquids in the EP 4th edition defines a Formazin Primary Opalescent Liquid Suspension (rated at 4000 NTU per EP 5th edition) as a solution of hydrazine sulphate solution and hesamethylenetetramine solution which is stable for 2 months stored in glass.

The EP 4th edition further defines a Formazin Standard of Opalescence (rated at 60 NTU per EP 5th edition) as a dilution of 15.0-ml of the Formazin Primary Opalescent Liquid Suspension (4000 NTU) to 1000.0–ml of water. This suspension must be freshly prepared and stored for no more than 24 hours.

To make the EP Reference suspensions or OP – Opalescence standards, the Formazin Standard of Opalescence (60 NTU) is mixed with distilled water in the following proportions to define 4 levels of liquid EPOP Opalescence Standards. Distilled water is nominally a fifth EPOP standard defining no opalescence or scattering.

Table 2.2.1-1 EPOP Standards 0 I II III IV
 Formazin Standard of Opalescence (60 NTU) 0.0 ml 5.0 ml 10.0 ml 30.0 ml 50.0 ml
Distilled Water (fill to 100.0 ml mark) 100.0 ml 95.0 ml 90.0 ml 70.0 ml 50.0 ml
NTU Rating 0 3 6 18 30

Sources for EPOP Liquid Opalescence standards are:

Hach Company

Loveland, CO 80538 USA


Hach offers the STABLCAL Reference Suspension Set that consists of a range for EP Opalescence Standards per EP is 0 (distilled water >0.1), 3, 6, 18, 30 NTUs. Given the 2-year stability, stabilizers will have been added to these liquid EP standards.

Hach STABLCALC set of EP Opalescence Standards

Hach STABLCALC set of EP Opalescence Standards

Another source for the Formazin Primary Opalescent Liquid Suspension (rated at 4000 NTU) and EPOP Liquid Opalescence standards (rated at 0 – ­30 NTU) is:

RICCA Chemical Company

Arlington, TX 76094 USA


Reporting of EP Opalescence using a HunterLab Sphere Instrument and EasyMatch QC Software

As of EasyMatch QC version 4.82 and higher HunterLab has implemented a correlation method to the EP Opalescence scale based on these standards and is able to report EPOP-10mm (D65/10) for liquid samples measured in a 10 mm path length transmission cell. EPOP values are reported to tenths of a unit, along with NTU values as well.

Do you know what Molten Color is?

FAQ:”A client is asking me to measure something they call “Molten Color’. Do you have any information on this? Do Hunterlab instrument have a function for this color?” Continue reading

Do you have references for the equivalency of CIE inverse instrument geometries?

FAQ: “…. the schema of the principle of measuring shows other way of light (source of light -> sample -> sphere -> detector) than our ColorQuest (source of light -> sphere -> sample ->  detector). Please can you explain me difference between both construction? difference between both results of measuring?”

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Can you explain the LabScan XE 0:45 inverted geometry?

FAQ: “Straight from the LSXE Pro-forma, the LabScan XE sample ports are described as:

Port Insert, 3-mm illuminated area; 5-mm measured area
Port Insert, 6-mm illuminated area; 10-mm measured area
Port Insert, 13-mm illuminated area; 17-mm measured area
Port Insert, 25-mm illuminated area; 30-mm measured area
Port Insert, 44-mm illuminated area; 50-mm measured area

I always thought that the measured area was smaller than the illuminated area. Have the illuminated/measured area in the Pro-forma been transposed? Seems like it!”

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Do you have a source for Magnesium Carbonate powder as top-of-scale?

For measuring the brightness of some materials, some dated industrial methods cite a Magnesium Carbonate block standard to be set to Y = 100% in reflectance. This is a very old top-of-scale standard and HunterLab does not recommend using it.

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