What is the best way to measure the effects of UV optical brighteners in our samples with our HunterLab instrument?
The recommended method is a two-part measurement sequence. The first measurement mode you will need to setup is the UVF Calibrated (UV included) mode. This mode will provide some UV content but will provide a consistent amount of UV content. The second mode you will need to setup is the UVF In (UV Excluded) mode. This mode will effectively exclude all UV content of the lamp.
After you take your two measurements in UVF Calibrated and UVF In you will then need to compare the significant indices you are concerned with for your product. For some customers this might be a L* value, a b* value, or maybe a WI index; this will be personal and depend on what your facility has established as a meaningful metric.
It is important that the UVF Calibrated mode is used because UV content in a lamp will vary from instrument to instrument and is affected by several factors. By using UVF Calibrated you are using a consistent UV content that will stay consistent as the lamp in your instrument ages. These settings could also be applied to different instruments should you upgrade down the line.