Coating Application, Materials, and Environmental Controls
Application is a controlled process
Coating application in nuclear work is controlled by the product data sheet and the project quality plan. Verify mixing ratio, induction time, pot life, recoat window, and thinning limits. Use stripe coats at welds, edges, and irregular shapes before full coats. Environmental limits usually include substrate temperature at least 3°C (5°F) above dew point, relative humidity within the product range, and adequate ventilation. Surface temperature, not air temperature, controls condensation risk. Traps include adding solvent to extend pot life, applying past the recoat window without surface preparation, exceeding specified wet-film thickness, and applying in high humidity because the air feels dry.
Rule of thumb: measure and record conditions before, during, and after application. If conditions exceed limits, stop.
Worked example: Air is 25°C and 85% RH, so dew point is about 22°C. A steel surface reads 24°C. That is only 2°C above dew point, below the 3°C rule; do not apply until the surface warms or humidity drops.