Emergence of wrinkles during the curing of coatings

TL;DR

This study investigates the formation of wrinkles in paint layers during curing, focusing on how solvent absorption causes swelling and delamination, leading to buckling and surface patterning.

Contribution

It introduces a simple model linking swelling-induced buckling and delamination to wrinkle formation, validated by experiments and linear stability analysis.

Findings

Wavelengths of wrinkles depend on solvent absorption dynamics.

Wrinkle emergence time correlates with swelling and delamination processes.

Model predictions align with experimental data.

Abstract

Wrinkles often emerge on a paint layer when a second coat of paint is applied on an already-coated substrate. Wrinkle formation occurs when the first layer absorbs organic solvent from the second layer. We set up experiments to mimic the double-coating process, focusing on the interaction between a paint layer and an organic solvent. In the experiments, we investigated the characteristic wavelengths of the wrinkles and the time of wrinkle emergence. We propose a simple model to explain (1) the buckling induced by swelling of the layer due to absorption of the organic solvent and (2) delamination of the layer from the substrate. A linear stability analysis of the model provides a relationship between the wavelengths and the characteristic timescale that agrees reasonably well with the data obtained from our experiments. Our results indicate that compression of the layer due to swelling and delamination are both important factors in the formation of wrinkles.