Why did my coating applicator get hard or crusty partway through the job?

Ceramic coatings begin to cure when exposed to air and moisture, and the coating absorbed in an applicator's suede or foam cures there too. As it hardens, the applicator spreads product less evenly and can even leave fine scratches on the surface. Change applicators when they stiffen, keep them covered between sections and do not try to reuse them for another session.