Coating Terms

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Dust free drying is defined as the shortest time which a dust dropped on a wet film will no longer stick to the surface. Tipping gently with the point finger on the film and the time at which paint does not adhere to the finger is the most frequently used test method to define dust free drying time. If this method is employed, before starting, the point finger should be wiped with a rag wet with acetone and the dampness and skin oil on the finger should be removed. A more practical method is starting a stopwatch after paint is applied. Cotton fibers are dropped on the wet test film from a height of 15 cm. After 10 seconds, cotton fibers are tried to removed by blowing over the test film. If no marks are left on the film, then stopwatch is stopped. Time passed is determined as dust free drying time and it is recorded with the ambient temperature. (e.g., Dust-free drying=5 minutes at 25°C)