1 Scope
1.1 This standard specifies a method for determining the degree of dispersion (usually expressed as particle fineness) of pigments in a paint-paint system, such as liquid coatings and their semi-finished products. It is also used to rate particle impurities in terms of cleanliness (or fineness) levels.

1.2 This standard is expressed in units of in/lb and the values given in parentheses are for reference only.

1.3 This standard does not describe the safety issues related to its application. Before using this standard, it is the responsibility of the user to formulate the corresponding safety and health measures and clarify the scope of application of the restrictions.

2 Reference Documents
2.1 ASTM Standard

D 1316 Test method for fineness of ink particles determined by NPIRI particle meter.

3 Overview of Methods
3.1 Wedge fineness plate The product with a scraper into the wedge scale slot, in some positions of the slot will see particles or aggregates of both. At the position where these particles form a certain shape, the reading is read directly from the scale. Cleanliness can also be given with this single groove scraper fineness meter (see 6.2).

The product is scrape into the stepped scale groove with a scraper. There are two upper sections on the fineness plate, each of which is about 6.5cm2 (lin2), with different depths. The number of particles deposited on the two sections is recorded; A reading of cleanliness (fineness) is also measured.

ASTM D1210-1996 Standard Test Method for Determination of Dispersion Fineness of Pigment-Paint Systems

4 Meaning and use
4.1 In the manufacture of pigment products, the pigment is usually dispersed in part of the paint on some kind of grinder. At this stage, it is necessary to determine whether the pigment aggregate has been fully broken, without affecting the smoothness of the coating film. This method describes the method by which such judgments are made.

5 Instruments
5.1 Wedge fineness plate A piece of tool steel, stainless steel or chrome plated steel (see Figure 1), approximately 170mm long and 15mm thick. The surface of the plate shall be flat and smooth, with one or two 127mm long scale grooves on it. From 10mm away from one end of the tank to the other end, the wedge shape of the layer depth from 100um to 0 is uniformly cut longitudinally, and the scale of the middle points is marked according to the depth. The suggested scale is the Hegman unit or um (note 1). This test method has three kinds of slots available:

5.11 Double parallel slots, 12.5mm apart on both sides of the centerline of a 65mm wide plate, with each slot 12.5mm wide (see Figure 1).

5.1.2 Single slot, 50mm wide, in the middle of the 90mm wide board (see Figure 1).

5.1.3 Single slot, 25mm wide, in the middle of the 65mm wide board (see Figure 1a).

Note 1: Other scales or calibrations of this fineness meter are also used in industry. In order to use those other scale readings that also report common unit values, some examples of those scale and depth proximity are given below.

ASTM D1210-1996 Standard Test Method for Determination of Dispersion Fineness of Pigment-Paint Systems

Sometimes the Hegman unit is mistaken for the Northern Standard scale.

② Approximately to 5um.

③ Paint Technology Federation (FSPT) value.

④ National Ink Research Institute scale (NPIRI) value. The scale on the NPIRI fineness meter is 0 to 10,

But many fineness gauges extend to 20 or 30 (see test method D1316).

Step fineness plate Tool steel, stainless steel or chrome plated steel (see Figure 1a), approximately 170mm long and 15mm thick. It has a 25mm wide slot in the middle of 65mm wide. Cut from the center along the length into two different depths, each half the length. The two depths are 75um and 25um or any other depth agreed by the buyer and the seller. There should also be two thickness marks at the distance of 25mm between the upper and lower sections of the ladder.

5.3 Scraper Tool steel, stainless steel or chrome-plated steel double-sided blade scraper (see Figure 2). 95mm long, 40mm wide and 6.4mm thick. It should be poured into a rounded corner with a radius of 0.38mm within 95mm from both sides.

5.4 Lighting Fixtures For visual observation, the fineness meter shall be illuminated by exposure tubes. It is placed 250mm above the fineness meter, the length of the lamp tube is parallel to the fineness meter, and the Angle between the fineness meter plane and the lamp tube is 75°~80°. You don’t need a light box; However, the design of the light box is given in Appendix A if needed.

ASTM D1210-1996 Standard Test Method for Determination of Dispersion Fineness of Pigment-Paint Systems

Maintenance and maintenance of fineness meter
6.1 Clean the fineness meter immediately after each use with solvent and a soft cloth, and keep it covered or packed when not in use. When it is idle for a long time, it should be oiled or wrapped with oil-soaked fabric to extend the use time.

6.2 Do not allow any hard material to touch or scratch the surface of the fineness meter, so as to cause nicks or nicks. Avoid other metal percussion or scraping.

6.3 The scraper may be worn or deformed, or the blade may be damaged or deformed so that it can no longer be used (note)

2); At this time, the knife edge needs to be replaced or readjusted.

Note 2: The wear or deformation of the scraper can be observed when the scraper edge is scraped along the smooth plane of the fineness meter, and then the sharp light behind the fineness meter can be used to check the edge: swinging the scraper back and forth will find that the contact is not good due to wear or deformation, and some light is exposed between the scraper and the fineness meter surface. Such a scraper is damaged and can no longer be used.

7 Visual criteria
7.1 A set of legends in Figure 3 illustrates six typical fineness patterns using the 5.1.1 two-slot fineness meter, which are regarded as standard patterns for the relationship between particle distribution and fineness value. Each DRAWN ARROW INDICATES THE END POINT (reading) of the distribution, and these patterns should BE viewed AS a reflection of the density of the particles, not interpreted as the size of the points. Although called “standards,” they are only used as examples of how fineness can be read, since no two particle distributions will ever be exactly the same.

7.2 Similarly, Figure 4 shows a typical fineness pattern using a 50mm fineness meter from 5.1.2 or a 25mm fineness meter from 5.1.3. These patterns are also applied like the double groove fineness meter patterns. It is also marked with a “cleanliness” rating. “Cleanliness” is a description of the number of particles appearing in the groove above the fineness value. There are three levels: A (0 to 8 particles), B (9 to 15 particles) and C (16 or more particles).

ASTM D1210-1996 Standard Test Method for Determination of Dispersion Fineness of Pigment-Paint Systems

8 Operation steps — Wedge fineness meter
8.1 Place the fineness meter on a horizontal anti-slip surface and wipe it clean immediately before the test. It should be confirmed that there is no cloth chip or fiber on the surface of the fineness meter.

8.2 Crack and shake the test material (Note 3) for 2min. Be careful not to stir bubbles into the paint. In order to get an accurate scratch reading, there should be no air bubbles in the test material.

Note 3: For the main purpose of this test method, the pigment particles in the test material should flow freely to the top of the fineness meter after pouring into the groove of the fineness meter. Therefore, the flow capacity of semi-finished products with high viscosity before the test is poor, so appropriate liquid should be used to dilute and reduce viscosity, and the viscosity reduction should reach the proportion of semi-finished products that are approximately the same as the viscosity reduction in practice.

8.3 Immediately pour the test material into the deep end of the tank, so that it slowly fills the tank. When using double groove fineness time, put test material in both upper grooves.

8.4 The two hand-held scrapers should be vertical and slightly inclined to their own direction to move evenly and briskly, and scrape the test material to the shallow end along the length of the groove. Apply only a light pressure to the scraper sufficient to remove excess material from the surface of the fineness meter. The test material shall be read according to the following methods within 10s:

8.4.1 Observe the fineness meter from the side perpendicular to the groove direction. Keep the fineness meter between the operator and the light source. The Angle between the fineness meter surface and the line of sight allows the image of the fluorescent tube to be displayed on the fineness meter test material.

Note 4: CLEAR varNISH may have TO BE VIEWED at a smaller Angle or shaded with a background or stain to allow better visibility of the particles.

8.4.2 Observe the first point in the sample that shows a clear pattern, but not the point of individual micro material (see Figure 3 and Figure 4). This is the reading of fineness. When using a two-slot fineness timer, take the average of the two slots and read up to 1/4 of the Hegman value. Take this average as a reading.

8.5 After the first scraping and reading, suitable test conditions and locations for fineness readings have been initially established. Repeat the above steps from 8.3 twice to produce two test readings. This process is allowed ONLY for a limited time interval between the pouring of the sample and the completion of the reading (when the time interval is more than 10s the reading cannot be used for reporting). The two readings were accurate to 1/4 on average

Hegman value (5um).

8.6 Interpretation of scatter graphs

8.6.1 Check the pattern and approximate fineness after the initial pour to ensure that the particle distribution is approximately the same as the point at the end of the standard pattern given.

8.6.2 Evaluate the cleanliness on a single tank, or compare it with a typical fineness pattern (only one level of Hegman value 6 has been shown, but it is practical to have similar levels at any level); Or count the number of particles appearing coarser than the selected fineness level (see 7.2 Cleanliness Range).

ASTM D1210-1996 Standard Test Method for Determination of Dispersion Fineness of Pigment-Paint Systems

9 Operation steps — step fineness meter
9.1 Place the fineness meter on a horizontal anti-slip surface and wipe it clean immediately before the test. It should be confirmed that there is no cloth chip or fiber on the surface of the fineness meter.

9.2 Shake the test material (Note 3) vigorously for 2min, being careful not to stir bubbles into the paint. In order to get an accurate scratch reading, there should be no air bubbles in the sample.

Note 5: For the main purpose of this test method, the pigment particles in the test material should flow freely to the top of the fineness meter after being poured into the groove of the fineness meter. Therefore, the flow ability of the semi-finished products before the test is poor, and appropriate liquid should be used to dilute and reduce viscosity, and the viscosity reduction should reach approximately the same proportion as that of the semi-finished products in practice.

9.3 Immediately pour the test material into the deep end of the tank, so that it slowly fills the tank. When using double groove fineness, put the test material in both grooves.

9.4 The two hand-held scrapers should move evenly and briskly vertically and slightly in the direction of rotation, and scrape the test material to the shallow end along the length of the groove. Apply only a light pressure to the scraper sufficient to remove excess material from the surface of the fineness meter. The test material shall be read according to the following methods within 10s:

9.4.1 Observe the fineness meter from the side perpendicular to the groove length. Keep the fineness meter between the operator and the light source. The Angle between the fineness meter surface and the line of sight allows the image of the fluorescent tube to be displayed on the fineness meter test material.

Note 6: CLEAR VARNISH MAY HAVE TO BE VIEWED at a smaller Angle OR shaded with a background or stain to allow BETTER visibility of the particles.

9.4.2 Count the number of particles between the ladder and the small mark on each side of the ladder. The counting area was 6.5mm2 (lin2). Use the following formula to calculate the fineness (cleanliness) of the sample, so that the mass of the coarse component (3mil side of the fineness meter) is 4 times that of the fine component (1mil side of the fineness meter) :

Delicacy (cleanliness) =10-int(c×0.4+f×0.1+0.9)

In the equation

c — Coarse composition (3mil side of fineness meter);

f — Fine components (1mil side of fineness meter);

int — takes an integer.

Note 7: It is recommended to only count up to a maximum of 20 on each side.

ASTM D1210-1996 Standard Test Method for Determination of Dispersion Fineness of Pigment-Paint Systems

10 Reports
10.1 Report the following information

10.1.1 Type of fineness meter used.

10.1.2 Get the average of the two readings as per 8.4.2 and report the um reading to 5um or/and the Hegman value to 1/4 units.

10.1.3 Method used to determine cleanliness.

10.1.4 Cleanliness level.

11 Precision and deviation

11.1 Precision — Coarse density has been determined by this method. The initial inter-laboratory tests that repeated the test of this method were valid; However, due to the dispersed nature of the data, new numerical analyses need to be done.

11.2 Bias -Because there are no true values, the bias cannot be determined.