HunterLab sphere instruments with CIE d/8 geometries conform to the requirements of ASTM D1003 Section 8: Procedure B Spectrophotometer. The measurement of transmission haze will be in close agreement with ASTM D1003 Procedure A Haze meter.
Transmission haze is a quantification of wide-angle scattering of light by a material in transmission. As an optical scattering phenomenon, transmission haze is dependent on the precise geometry of the instrument, that is the relative arrangement of light source, sample plane and collector/detector. The industry standard instrument for haze measurement is ASTM D1003 Standard Test Method for Haze and Luminous Transmittance of Transparent Plastics written around the historic Haze meter design that has 0°/diffuse geometry, a 30-mm diameter port and defined collection angles.
Our colorimetric spectrophotometers and the Haze Meter both have sphere geometries but are not identical in construction. As stated in ASTM D1003 Procedure B, conforming instruments (Table 4) such as HunterLab UltraScan PRO, UltraScan VIS and ColoQuest XE d/8° sphere instruments, will agree closely with the Hazemeter at the low near clear end (near 0), to a gradual bias of 2.5 units at the upper level of the method where Haze% = 30.
HunterLab USPRO, USVIS and CQXE spectrophotometers are built in conformance with the CIE requirements for a d/8° sphere geometry. In addition to Haze%, they can measure product L*, a*, b* color and color differences, Yellowness Index, Y transmission of transparent solids and liquids. They can also measure color in reflectance.
This graph shows HunterLab sphere instruments (UltraScan PRO, UltraScan VIS and ColorQuest XE) reading a set of plastic haze standards calibrated using an ASTM D1003 Haze meter.
As you can see the agreement is excellent and linear, particularly at the low end which is where clients have the most concern. The variation between the read and calibrated values is minimal.
Side-by-side testing between a D1003 Part A Haze meter and one of our sensors is required to verify haze readings on products. On flat, transparent plastic plaques, a HunterLab D1003 Part B sphere spectrophotometer will read haze closely to a D1003 Part A Haze meter and provide a variety of other useful color information. HunterLab sphere instruments also measure in reflectance (applicable to opaque and translucent plaques) as well as transmittance (transparent plaques). In comparison, a Haze Meter measures only Haze% and Y Total.
FAQ: “I want to share my results from reading a set of haze standards since my system seems to be reading about 10% low for haze at the upper levels. I am not too concerned about this (especially since I tend to get samples <5% haze).
For an ASTM D1003 Part B instrument, your results are correct.
HunterLab always recommends a PQ Performance Qualification step of reading back the top-of-scale standard, It should read Haze% = 0, Y Transmission = 100 to verify that the instrument is performance qualified to measure samples.