Organic coatings clustering, water

Water can be contained inside an organic coating in two states either bound to the matrix or in microscopic water-filled cavities, known as clusters. Temperature, and particularly the glass transition temperature, Tg, greatly influence the solubility of water in the coating. The formation of clusters seems to be enhanced by a loss of solubility resulting from a decrease in temperature across Tg [35]. 

The causes of proceeding delamination underneath organic coatings can be roughly categorized in two types delamination due to clustering of water at the interface and delamination caused by specific corrosion processes that produce either low or high... 

The wax patterns are cleaned with water or organic solvent and coated with a wetting agent, which helps the ceramic slurry to adhere to the wax. The cluster is then dipped in a liquid ceramic slurry, stuccoed with granular silica, zircon or alumina/silica refractories and then dried before the application of the next coat. The coating process is continued until a sufficiently thick shell is established. 

Alternatively, the addition of polar solvents to hydrocarbon-based paints will improve the solubility of the thickener molecules, and decrease the chance of particles or clusters of molecules forming because of borderline solubility. This will lessen or even remove the effectiveness of the thickener. Again the same principles apply to aqueous coatings additions of water-miscible organic solvents (e.g. ether-alcohols) increase the solvency of the medium for the hydrophobic portions of the associative thickeners and lessen their tendency to associate. 

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