In this series of blog notes we have discussed what is needed to quantify color and how light sources are quantified. The second element of the visual observing model that must be quantified is the object that modifies the white light source. Continue reading
FAQ: “A client gave me 3 equal size diamonds for color measurement and I have measured them using a reduced sphere exit opening Continue reading
HunterLab instruments measure the color as it relates to the quality of the product. To be able to begin to measure and quantify color we have to know more about why colors appear as they do. As humans we all see and perceive color differently; this is because the human perception of color is a psychophysical response. The visual observing situation model shown above illustrates the three components necessary for the perception of color. Continue reading
FAQ: “What is a visual limit for Haze%? When should I be able to see a difference in a sample?”
A perfect clear of 0% would be air for transparent solids and the transmission cell of a defined path length filled with DI water for transparent liquids.
It should also be noted that the Haze% measurement of scatter in a sample is dependent on the thickness of transparent solid samples or cell path length of liquid samples.
The answer as to when you can see a visual difference will depend on the nature of the sample. For the plastic or glass sheets used in computer tablet screens, acceptable limits for what is faintly visible fall in the 1-2% range.
For pharmaceutical or chemical liquids, the average person may be able to see a visual difference in transmission haze at around 4 – 5%, and should definitely see a difference at a level of 6 – 7%.
To determine this for you sample, you should take a range of products exhibiting haze and get the consensus opinion of a number of people as to which samples show less than and more than visible sample. Measure Haze% using a sphere instrument and assign a visible limit specific to your product.
For many applications, especially those related to consumer products, a visible limit for haze is also the tolerance for acceptable product but not always…
Depending on the end use of the product, what is an acceptable may be below a visible limit if you don’t customer to see any visible haze difference in your product.
Or, if haze is inherent in the product and whatever is causing the product haze does not impact its use, an acceptable tolerance may be several times a visible difference. On these types of products, a typical range for good product might be from 10 to 12%, with an upper limit set at 20% just to ensure that any abnormal product is detected.
Air for transparent solids, or the cell filled with DI water or clear solvent for transparent liquids, is a physical product reference representing no haze, and the best your sample can be. A visible limit in product samples will typically be in the 2% to 5% range. What is acceptable in the marketplace will vary from less than a visible limit to some upper maximum.
Here is how to think of IQ OQ PQ being applied in general for all HunterLab instruments. Continue reading