What Does Dry-to-Recoat Time Mean?
Dry-to-recoat time is the length of time it takes for a freshly applied coating to reach that drying stage at which another coating can be applied without incurring any surface irregularities such as loss of adhesion, blistering or lifting.
Dry-to-recoat time is determined through tests methods that are widely recognized but not by all industry experts.
The range of minimum to maximum dry-to-recoat times that correspond to variables affecting drying time (e.g., temperature) are usually found on the coating materials’ container or product data sheet.
The coating has not yet fully cured at dry-to-recoat time.
Corrosionpedia Explains Dry-to-Recoat Time
Dry-to-recoat time is an important factor when buying paint and other coating materials as it is an estimate of the time when another coating layer can be applied without encountering problems like wrinkling or lifting. It ensures that the film to be coated is dry enough so that:
- The solvent in the new coating does not soften the previous coat and weaken the bond between the two layers.
- There will be no moisture or solvent trapped in the film to be coated over that may delay complete curing.
There is no single standard, but several test methods are currently used to determine dry-to-recoat time. The following are recognized by some but not all groups within the industry.
- ASTM D 1640: Test Methods for Drying, Curing or Film Formation of Organic Coatings at Room Temperature – This is also called the drying time by finger method and is the most commonly used method to determine the time for the eight stages of the drying process.
- The Federal Test Method Standard141C Method 4061.2 Drying Time - This method is similar to ASTM D 1640 but it has no procedure for dry-to-touch time. It is similar to the Paper Test method except for the weight used.
- ISO Standard 9117: Paints and Varnishes – Determination of Through-Dry State and Through-Dry Time – This test determines if the coated material has reached the “through-dry state” using a specified instrument.
- Specification DIN 53 150, Determination of Drying Time of Paints - This is a German Standard, where DIN stands for "Deutsches Institut für Normung" (German Institute for Standardization). The drying stages are identified as Stage 1 through Stage 7.