This precision instrument is used to determine particle size and the fineness of grind of particles in printing inks.
The NPIRI gauge and its scraper are made of hardened stainless steel and the gauge has two grooves with a gentle slope.
The groove width is 25mm (0.98") and the groove length is 165mm (6.5"). The NPIRI scale is displayed alongside the microns scale.
For an instructional video,
copy and paste this link: https://www.youtube.com/watch?v=kA4-srdjGFQ