Lucideon Helps Varnish Manufacturer Test for Rheological Properties During Setting

Varnishes are used on a variety of surfaces to both protect substrates from weathering and to provide good aesthetics. In developing improved formulations, there are a number of important properties demanded including:

  • fast diffusion of brush marks where application is by hand
  • some degree of yield stress to avoid flow on vertical surfaces
  • fast setting.

The Challenge

Lucideon’s client wanted to develop new rheological protocols that allowed all such aspects to be monitored with a view to using this data as part of future development work and quality control.

What we delivered

Working with the client our experts recognized that lowering a plate or cone onto a baseplate (at an optimized gap distance approaching the typical thickness of applied layers) with a fresh varnish sample squeezed between them, provided some useful “as applied” information. They also recognized that, having performed the initial measurement, the small gap between the plate (or cone) and baseplate represented a closed environment not too dissimilar from the sample remaining in the tin. Therefore, we developed a protocol for repeatedly lifting the cone or plate, to retain the applied thin layer of varnish and allow it to be exposed to the atmosphere for different times. After each lift, the upper cone or plate was lowered again and a new measurement made. As the varnish began to set, the nature of the rheological measurement changed to provide quantification of the increasing elastic behavior.

Value to the Client

The protocol we developed allowed us to fully characterize the current best formulations as a benchmark for the client. Using the same protocol, the client is now continuing to work with us to gain insights into how formulation changes affect product rheology. These changes can be correlated to feedback from users (good or bad).

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