Determining Dryness During Special Coating Application
Specialty coatings are used in environments with unique conditions, which may expose them to more severe vibrations, abrasion, deformation, and complex corrosive media, as well as abnormal temperatures. The drying and curing process is fundamental to the performance of the coating, thus playing a crucial role in the construction process. To achieve good adhesion, a complete and dense film, and to meet the designed strength, flexibility, hardness, and special functions of the coating, it is highly recommended to read and save this article. Generally, the drying and curing process of the coating is divided into the following three stages based on the curing degree:1The surface feels slightly sticky upon light touch but no paint adheres to the hand.2Semi-hard Dry (Dry to the touch): Applying pressure with the fingers does not cause stickiness, and the coating does not shift.3Totally Dry: Gently scrape the coating with a finger, leaving no marks.
The three stages of "drying," "drying properly," and "fully dried" illustrate the concept of coating dryness, dividing the drying process of the film into intuitive tactile categories, making it highly suitable for use and evaluation on construction sites. It is also used for on-site quality checks of the coating. In the coating application process, the curing level of the film can be further refined and categorized as follows:1Touch-Dry: The coated paint film does not adhere to fingers when lightly touched.2Surface dry: Dry to a state of no sticky dust.3Semi-rigid and dry: Light pressure does not leave fingerprints on the coated film.4Totally Hard and Dry: The coating paint is finger-resistant under high pressure.
5Dry to the point of being grindable.6Completely Dry: A state of complete dryness with no defects. During the actual construction process, there are many factors that affect the drying speed of the coating. Generally, the following aspects are considered:1Coating Types: The curing speed of different types of coatings can vary greatly.2Coating Thickness: Applying too thick a coat in one go is不利于drying.3Temperature: The impact of temperature is the most important among all factors. High air temperature around the coating, high surface temperature of the substrate, or high temperature of the coating itself will all affect the drying speed and film quality of the coating.
4Relative humidity: Most paints are suitable for application when the relative humidity is45-60%The air's humidity level should be dry. If the air is too humid, not only will the drying process be slow, but the paint film will also be blurred and unclear, with a high likelihood of the coating developing a "whitening" effect. The importance of paint for protective coatings is even greater.
5Ventilation Conditions: Good air circulation aids in the evaporation of solvent in the coating and the expulsion of solvent vapors, ensuring safety in the drying area. The ventilation speed and wind direction (horizontal or vertical) both affect the quality of the paint film. The quality of air supply and the wind pattern on the coating surface must be calculated and tested; arbitrary air flow is not allowed to prevent affecting quality. Each type of paint has a reasonable drying time under specific drying conditions, and it is not mandatory for any variety of paint to dry quickly. Instead, one should carefully select and determine the modification procedures based on experience, and strictly follow the drying and curing conditions specified in the paint application instructions before proceeding. The Xuchang Infrared Institute will continue to maintain its research and development of infrared radiation heating technology to enhance safety, efficiency, reliability, and system lifespan, providing you with genuine infrared heating technology solutions.
