Here it is from RB;
When applying additional coats of a Rust Bullet coating, the previous coat should not be wet or tacky; if you are unable to transfer the coating to a gloved finger, the surface is ready for an additional coat. Approximate drying time between coats is two (2) to four (4) hours for Rust Bullet, and six (6) to ten (10) hours for BlackShell, depending on humidity levels. When excessive wet film is applied, additional cure time will be necessary. Rust Bullet Coatings are moisture sensitive; in high humid conditions of 80%+, Rust Bullet will cure much faster than it will in lower humidity. When applying additional coats from one day to the next, especially in the morning, make sure there is no dew or condensation on the previous coat. The surface to be coated must be completely dry. It is important that corners, edges, and heavily pitted areas are adequately covered. When Rust Bullet cures, it pulls tight to the center; therefore, it is particularly important that edges and corners are sufficiently coated.
Rust Bullet® Rapid Fire Accelerator can be added to the Rust Bullet Standard and Rust Bullet Automotive formulas to decrease the normal recoat time of 2 to 4 hrs to approximately 30 to 40 minutes per coat; and to Rust Bullet BlackShell to decrease the normal recoat time of 6 to 10 hours to approximately 1 hour. Rapid Fire makes it possible to apply multiple coats of Rust Bullet in a single day and reduces project completion time by as much as 80%. Rust Bullet coatings accelerated with Rapid Fire are designed for spray applications and can be applied with either an HVLP Spray System or an Airless Spray System.
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