Rhopoint ID Application Notes – Distance Related Haze
Overview
Optimising the optical properties of a packaging film for food applications is essential to ensure the food product underneath can be clearly seen. Many materials have transmission properties which vary dependent on whether the material is in contact with or at variable distance to a viewed object. As consumers are very selective concerning their choice and eventual selection of a packaged food any distortion or hazy effect in the packaging film will make the product less appealing having an effect as to whether the item is purchased.So that the item can be viewed clearly and with good sharpness the film should have minimal haze at the viewing distance set by the packaging container.
To the right it can be observed that without a film covering the food in the left half of the packaging can be seen very clearly, whilst on the right the food with the film appears milky indicating that haze is present.
Measurement using traditional hazemeters according to the ASTM D1003 test method quantifies haze at a fixed distance, therefore any distance related haze effects cannot be detected or evaluated. Thanks to the imaging- based system of the Rhopoint ID, measurements can now be easily and accurately made to determine distance related haze properties of the film. To match any user specific application the Rhopoint ID can measure HID at any distance from 0-30mm allowing the peak obfuscation distance to be determined which is usually between 0.7 and 25mm.
Process
Example – BOPP Film
A customer supplied sample of BOPP film was
tested. A range of spacer mounts available as
optional accessories can be used allowing the
measured height of the film to be adjusted over
the range 0 – 30mm in steps of 2mm.
As some mounts are magnetised they
conveniently locate and hold the sample at each
measurement height.
STEP 1: The abraded sample was mounted onto the table and a measurement taken.
STEP 2: Then 2mm spacers were placed underneath the film to sequentially increase the measurement distance.
STEP 3 to 7: This process was repeated until there was no noticeable change in the measured haze value.
Results
Example – BOPP Film
Measurement Results
Observations of results
The measurement results provide valuable data to determine the haze variation and the maximum peak haze value of the film over a distance range. The addition of images allows visual comparison of each measurement due to the change in distance. Matching the material exactly to the application allows quality improvements and cost savings.