The following steps may be done during manufacturing in order to prevent Film Cracking (Type 2): I. Improve drying (reduce spray rate or increase temperatures) to offset overwetting. II. Increase pan speed to minimize dwell time in spray zone. III. Use high solids coating systems to reduce moisture burden on drying process. IV. Reduce processing temperatures to minimize core thermal expansion.

• A. All statements are correct
• B. Only ONE statement is correct
• C. Two statements are correct
• D. Three statements are correct

Answer: (D)

Film cracking Type 2 is driven by how the coating dries and how stresses develop as the film forms on the moving surface. The goal is to manage the amount of moisture in the film and how quickly it dries, so the coating shrinks evenly rather than forming cracks.

Improving drying to offset overwetting makes sense because if a coating is excessively wet, it dries unevenly and can develop internal stresses as the solvent leaves. By reducing spray rate or boosting drying capability (for example, higher temperatures within safe limits), you remove moisture more consistently, keeping the wet film thinner and the drying more uniform, which helps prevent cracks.

Increasing pan speed reduces the time any given area spends in the spray zone. Less dwell time means the coating is thinner when it enters the drying path, reducing moisture buildup and the likelihood of nonuniform drying and stress hotspots that lead to cracking.

Using high solids coating systems lowers the amount of water or solvent in the coating from the start. With less moisture to remove, there’s less shrinkage-related stress during drying, decreasing the chance of film cracks forming.

Reducing processing temperatures to minimize core thermal expansion sounds like it might help, but it typically slows drying and can worsen nonuniform drying and moisture-related stresses. It also limits the ability to control solvent evacuation effectively. In practice, this approach is not a reliable way to prevent Film Cracking Type 2, whereas the other three steps address drying rate, film thickness, and solvent load more directly.

So, I, II, and III are the effective steps, while IV is not.