Bare metals are classified as opaque metals and do not allow any light to pass through them. In opaque metals, the specular reflection and diffuse reflection are key to defining the light interaction of this unique sample type. For bare metals both color and gloss are seen in the specular reflection which makes up a large portion of the reflection. Continue reading
HunterLab manufactures, directional 45/0 instruments and also diffuse sphere instruments, with diffuse/8˚ geometry. The UltraScan PRO, UltraScan VIS, ColorQuest XE, and ColorQuest XT are all bench top sphere instruments available from HunterLab. Continue reading
FAQ: ASTM D6290 recommends that I measure my plastic pellets for yellowness using the specular exclude mode. What is this?
FAQ: “More customers are asking us about Chinese Pharmacopeia Numbers… is this similar to EP/USP Color?
FAQ: “Do you sell a depolarizer for my HunterLab sphere instrument? On occasion we test polarized samples and there is definitely a dependence on the orientation of the lens. I was wondering if adding a depolarizer would eliminate this phenomenon?”
FAQ: “What is the limit on the standardization in TTRAN. Using the small sample flask, filled with Ultra pure water. If they follow the protocol, they expect to find values (CieLab: 100.0; 0.0; 0.0)?” Continue reading
FAQ: “Do we have to keep the white tile at the reflectance port during transmission readings?” 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.