EN ISO 2884-1 Paints and Varnishes - Determination of Viscosity Using Rotary Viscometers - Part 1: Cone and Plate Viscometers Operated at High Shear Rate

The standard "EN ISO 2884-1 Paints and varnishes - Determination of viscosity using rotary viscometers - Part 1: Cone and plate viscometers operated at high shear rates", based on a European standard and published by the International Organization for Standardization (ISO), is one of a series of parts dealing with the sampling and testing of paints, varnishes and related products. This standard complements the standard "ISO 2431 Paints and varnishes - Determination of flow time using flow cups".

This standard describes the general procedure to be followed in determining the dynamic viscosity of paints, varnishes, and related products at a shear rate between 9,000 s⁻¹ ^and 12,000 s⁻¹ ^. The resulting value provides information about the material's resistance to brushing, spraying, and roller coating during application. The described procedure is applicable to all paints and varnishes, whether or not they exhibit Newtonian behavior. Materials containing dispersions of large particles will produce erroneous results.

This procedure utilizes a cone and plate geometry viscometer operating at a shear rate between 9,000 s⁻¹ ^and 12,000 s⁻¹ ^. The actual apparatus used is agreed upon between the parties, and details are specified in the test report. A simple apparatus for routine use is described in the standard appendix (Appendix A).

In the tests, a representative sample of the product to be tested is taken as described in the ISO 15528 standard. The sample is then examined and prepared for testing as described in the ISO 1513 standard. If the sample has a tendency to sediment or separate during storage, it is mixed until homogeneous, taking care not to contain air bubbles. There should be no foreign matter or lumps in the sample. The sample volume should be sufficient to fill the space between the cone and the plate. Samples containing large particles will produce abnormal results and may damage the instrument. For cone and plate viscometers with truncated cones, the large particles in the sample should be smaller than one tenth of the space between the cone and the plate.

The device should be checked regularly in accordance with the manufacturer's recommendations and experience gained in using the device, comparing the results with those of previous checks to determine the required check frequency. The results are checked using standard refined mineral oils with Newtonian properties and known viscosities (three mineral oils with viscosities between 0,05 Pa.s and 0,5 Pa.s, approved by an approved laboratory, are used). The cones should be checked regularly for wear and replaced if they show signs of scoring or, for uncut cones, if they show signs of flattening.

If the readings obtained differ by more than 5 percent from the known viscosities of standard oils, the instrument should be checked by a qualified instrument engineer or returned to the manufacturer for adjustment. Silicone oils should generally be avoided because of their tendency to foul instruments and the possibility of shear thinning behavior at high shear rates.

To check that the temperature does not change during the determination, the determination specified in this standard is carried out with the standard oil having the highest viscosity indicated on the scale reading. The viscometer is allowed to operate with this oil for 5 minutes, after which the reading should not have decreased by more than 10 percent. If the decrease is greater than 10 percent, the instrument is not suitable as set up for the determination of viscosities at high shear rates in accordance with this standard.

The procedural steps are as follows:

Immediately after the sample has been prepared in accordance with this standard, the following sequence of operations is carried out twice, first allowing the instrument to warm up in accordance with the manufacturer's instructions. When comparing the viscosities of the products, the shear rate should be the same. Unless otherwise agreed, the determination should be made at 23 degrees plus/minus 0,2 degrees.
The temperature of the fixed part of the viscometer is set to 23 degrees plus/minus 0,2 degrees or alternatively to an agreed temperature. An appropriate amount of the product to be tested is transferred to the appropriate part of the viscometer, taking care to avoid the inclusion of air bubbles, and the other part is adjusted to the correct position. The time required for the sample to reach the agreed temperature is waited, depending on the device used.
The rotor is started and the reading on the balance is recorded when the reading becomes stable. If the reading does not become stable after 15 seconds, the 15 second reading is recorded and the absence of a stable reading is noted in the test report.
If the reading does not directly indicate the viscosity, the reading is multiplied by the appropriate conversion factor or a suitable calibration curve is used to obtain the viscosity.

The results of two determinations taken shortly after each other, by the same operator in the same laboratory, with the same instrument, should not differ by more than 5 percent from their average.

Our organization has a strong staff that closely follows the developments in science and technology in the world and constantly improves itself. Among the numerous test, measurement, analysis and evaluation studies provided for businesses in various sectors, there are also test services in accordance with the standard “EN ISO 2884-1 Paints and varnishes - Determination of viscosity using rotary viscometers - Part 1: Cone and plate viscometers operated at high shear rate”.