FAQ: "I see that you sell haze standards for 1% to 30% haze. In your application notes there are several entries about >30% haze. For low haze however, do you make custom standards with haze less than 1%?"
I am sorry but we do not for the following reasons.
All 1% Haze standards are not the same. The 1% Haze value is a nominal value such that when calibrated, a 1% Haze standard could have an assigned calibrated value of say 0.79% or 1.24%, as the standards themselves has some inherent variability when it comes to scattering.
The second point is that HunterLab sphere instruments are standardized in TTRAN transmission on Air for measuring transparent solids such as a plastic plaque, or if measuring transparent liquids, on a transmission cell filled distilled water. These top-of-scale standards represent a perfectly clear colorless material.
As a PQ Performance Qualification step, we always recommend our customers read back the top-of-scale standard (Air, or cell + distilled water) as a sample with the expectation that this clear and colorless reference should read L* = 100, a* = 0, b* = 0 indicating no color, and Haze% = 0, YTotal =100, indicating no transmission haze or scattering. If you read these values closely, you are performance qualified to proceed to measure production samples.
As a second PQ step, you could read one of these calibrated Haze standards with the expectation that you would read closely to the calibrated value.
These two PO steps are the basis for validation of transmission haze measurement on your HunterLab system at the low end of the transmission haze scale prior to making production sample measurements.
Also, in general, measured differences in Haze% of less than one unit are not considered significant as measurement variation (sample replacement and scattering non-uniformity in the sample) can account for a 1% Haze difference even in a uniform sample.
A visual difference in haze is typically in the range of 4% to 5% Haze before it becomes visually apparent in a sample.