Determining the consistency (viscosity) of lacquers by finding out the discharge period through outflow crucibles
The procedure is based on the ČSN EN ISO 2431 standard – Paint materials – determining the discharge period through outflow crucibles. This standard is a Czech language version of the EN ISO 2431:1996 standard.
Note: For some practical reasons we opt to make slight deviations from the standard. Primarily, the outflow crucible does not altogether conform with the standard; the outflow nozzle is different length. The standard demands the length to be 20 mm. Our company utilizes one which has 4 mm in length and 4 mm in diameter. The aim here is to reach compatibility with the measurement procedures with our customers. As far as we know, they all use crucibles with the ø 4mm x 4mm nozzle.
The measurement temperature: 20 ± 2°C.
PROCEDURE:
- Both the sample and the crucible to be tempered to the temperature of 20 ± 2°C. The temperature reached to be checked by measuring the sample.
- The crucible to be clamped in the frame and filled with the lacquer in such a way as to eliminate creation and content of bubbles. The nozzle shall be plugged up with a finger.
- The meniscus which has developed to be wiped off with a spatula into the groove.
- An appropriate vessel to be placed under the crucible and the finger goes out of the nozzle. At the same moment the stop watch is started.
- A flow of the lacquer out of the crucible is observed and the stop watch to be stopped once the flow has been discontinued for the first time.
- The time measured to be rounded off to the whole seconds.
Note: The consistency of some lacquers may be partly altered in the course of time. This is why there may be deviations from the values declared in the Certificate of Quality.
The resulting value is given in seconds at a temperature of 20 ± 2°C.