Adhesive Coating, General Rules

Adhesive Coating, General Rules 2.3.1. Different Methods... 

It should be noted that excessive amounts can impair flow of the dispersion, which rapidly results in flaws (pinholes, fisheyes) in the coating. A general rule of thumb is that the amount of antifoam in initial experiments is 10 % of the amount of wetting agent, i.e., for example, one part of wetting agent and 0.1 part of antifoam per 100 parts of dispersion. Owing to interaction with the auxiliaries in the dispersion, the most effective antifoam for each adhesive must be determined experimentally. 

As a general rule, acceptable adhesion is achieved if the surface energy of the substrate that is, the ability to attract a liquid, is 10 dynes/cm higher than the surface tension, i.e., the resistance to spreading of the coating, ink, etc., of the liquid. In this situation, the liquid is said to wet out or adhere to the surface. 

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