The importance of the right environment for the application, drying and conditioning of coatings prior to testing

Laboratory tests of coatings are intended to provide knowledge about the properties of paints after they have formed continuous layers. These properties, which vary depending on the type of paint and coating, include scrub resistance, hardness, flexibility, and resistance to accelerated weathering.

Coatings in climatic chamber at Spektrochem Paint R&D Laboratory

The coating formation process, depending on the type of binder system and formulation, takes place under certain conditions. In some it is less, in others more optimally, but in virtually every case the temperature and air humidity to some extent always influence the quality of the coating formation. It especially applies to water-based paints.

Thus, if the coating formation process depends on the conditions under which it occurs, the results of the laboratory tests obtained will also depend on the quality of the coating formation. That is why I decided to use the example of our laboratory to describe the exemplary process and conditions during the application, drying and conditioning of coatings for tests in laboratory conditions.

Coating immediately after automatic drawdown under standardized conditions

The repeatability of the tests depends to a large extent on the conditions in which the coatings are applied, in which they dry and are conditioned during the tests. Of course, there are also other components, such as the test method, instrument calibration, measurement uncertainty, experience of the technician, etc.

The Spektrochem laboratory uses advanced equipment for air humidification, purification and dehumidification, which, together with the air conditioning and gentle air circulation system, provides the conditions required by the following standards:

  • ASTM D3924-16(2019) Standard Specification for Standard Environment for Conditioning and Testing Paint, Varnish, Lacquer, and Related Materials
  • CEN EN 23270:1991 Paints and varnishes and their raw materials – Temperatures and humidities for conditioning and testing (ISO 3270: 1984)
  • CEN EN 1062-11:2002 Paints and varnishes – Coating materials and coating systems for exterior masonry and concrete – Part 11: Methods of conditioning before testing

The following video gives an overview of our quality assurance for temperature and humidity in the laboratory. This video provides an overview of our entire range of standards for maintaining temperature and humidity throughout all laboratory operations.

Constant conditions prevail not only in climatic chambers but in the entire laboratory. A set of sensors and loggers records the air temperature and relative humidity 24 hours a day, with the temperature being recorded both in °C and °F. All recorders are regularly calibrated in accordance with NIST standards, thanks to which appropriate corrections are made to each reading and the obtained data are reliable for the entire laboratory room.

Below is an example of one of the 7 day temperature recorders during the drawdown and drying of the coatings for the ASTM D2486 test.

And a record of changes in relative air humidity over the same period.

We believe that a refined example of our temperature and humidity control and a system of their constant maintenance can be an example for others who want to obtain similar conditions to ours, and above all, it is the reason for the provision of the highest quality laboratory testing services by our paint and raw materials testing laboratory.

Published by Artur Palasz

Scientist, paint formulator and testing expert.

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