In its simplest conception, a Fineness of Grind Gage may be considered essentially a continuous variable screen. It can be readily seen that if a material such as fine silica were distributed uniformly in a single particle thickness in the gage path, these particles would protrude above the sides of the path starting at whatever point that their physical size exceeded the depth of the path.

If a straight edge scraper was brought to bear on the sides of the path in conjunction with the deepest part, and then moved slowly down the path to the shallow end, it would contact the protruding particles and on continued movement, screen or push these particles from the path.

The Fineness of Grind Gage can be used for checking the particle size in a paste. The sample paste is used just as it comes from the grinding machine, but first permitted to cool to room temperature. When this is done, it will be found that reading the gage has been reduced to the simple task of observing where the coarse particles have been screened out, their path being a definite scratch in the paste matrix. Since most pastes show little fluidity in such a thin film, most materials will dry in the path before confluence erases the scratches. Little difficulty is experienced in obtaining agreement between various trained personnel regarding readings taken by this method.

Paint Club Scale

The Paint Club Scale is similar to the Hegman Scale in that it also has a range of .004 inches; however, this range is divided into ten parts instead of eight parts. The "0" is at the .004 inches depth and the "10" is at the infinite point on the path. This scale was developed by, and is recommended by, the New York Paint Club, Subcommittee No. 23.

Mils Scale

The Mils Scale has been the common denominator through which we have interpreted other scales. On Fineness of Grind Gauges 1 Mil equals .001 inches.

Microns

For our purpose on Fineness of Grind Gages, one Micron has been rounded to .00004. Thus, one Mil equals 25 Microns.

The NPIRI Scale

The NPIRI Scale is a scale designed for ink gauge by the National Printing Ink Research Institute. The scale begins with "0" at the infinite point and extends to "10" at a depth of .001 inches. While it is an arbitrary scale, it is a logical one in that these divisions are equivalent of tenths of mils, or 2-1/2 microns. This scale has been extended for use on Modified Ink Gauges of greater range which are used by some companies for premix control and inks having particles or agglomerates outside the range of the NPIRI Production Grindometer.

1. Block sizes shown are approximate.
2. Path length shown is the length of the calibrated section only.
3. Hegman Scale is designated “NS” on gages manufactured prior to 1969.
4. Hegman Scale is designated “H” on gages manufactured after 1968.
5. Though one micron equals .00003937 inches, we have rounded off to .00004 inches for calibration.
6. All gages and wedge plates are supplied with adco stype scrapers (A1, A3, or A4) in correct width.

Used for a variety of hot-melt applications, the heated grind gage may have any desired range or scale arrangement on a 2-1/2" or 3-1/2” wide gage. It is supplied with an insulated model A-1 scraper.

The aluminum base is heated by a Chromalox cartridge element of 60° to 250°F range. A 50° to 300°F thermometer monitors the temperature of the gage. The 110V cord is heat and chemical resistant and grounded.

• Cosmetics
• Ceramics
• Clays
• Adhesives
• Chocolates
• Dyes
• Talcs

• Resins
• Silicates
• Flours
• Carbon Blacks
• Micas
• Oxide Coatings
• Plastisols

• Paint & Varnish
• Inks
• Chemicals
• Peanut Butter
• Pharmaceuticals
• Phosphorescents
• Paper Coatings

• ASTM D 1210
• ASTM D 1316
• ASTM D 333
• FTMS 141a Method 4411.1

• DIN 53-203
• ISO 1524
• BS3900: Part C6