Introduction to ASTM D823
The procedures for attaining a consistent coating thickness on test panels are described in the ASTM D823 standard. Techniques include applying coatings with automated spray equipment or handheld instruments while regulating variables including substance viscosity, traverse speed, and fluid supply rate. These procedures are essential for assessing coatings meant for field or industrial applications, particularly when it comes to the visual characteristics of metallic coatings, such as color and shine. MaTestLab is one of the best testing service providers, with the best network of testing laboratories in the USA to carry out ASTM D823 tests for our clients. The scope of ASTM D823 covers five distinct film preparation procedures that guarantee accurate and consistent results when measuring coating thickness on test panels.
ASTM D823 Test Methods
The test proceeds as follows:
| Apparatus Setup | It entails putting the spray gun on the sprayer that is automated. The spray gun’s air input is connected to the air pressure gage, which is connected to the air line hose from the regulator. The distance between the gun tip and the test panel surface is 200–300 mm. To get the required air pressure, which is normally between 40 and 75 psi, the air regulator is adjusted. The traverse speed of the gun mount is controlled by the automated spray machine controls. |
| Measurement of Thickness | A wet film thickness gauge is used to measure the wet film thickness. After that, the dry film thickness is determined using magnetic or eddy current gages. |
ASTM D823 Test Specimens
| Specimen Details | Clean, flat, stiff substrates in a range of sizes that may fit in the automated spray machine’s panel holder serve as specimens for coating testing. |
| Specimen Preparation | The specimens are cleaned properly and handled very carefully to avoid recontamination. To prevent surface damage, specimens with metallic or organic coatings are not excessively clean. The procedures for specimen preparation are conversion coating, vapor degreasing, solvent brushing, solvent wiping, and alkaline cleaning. |
| Specimen Dimensions | ASTM D823 states that the test panels should be of a size that can be accommodated by the automated spray machine’s panel holder. |
ASTM D823 Test Results
ASTM D823 findings provide information related to the type of coating material, number of spray passes, air pressure, temperature of the coating material, thinner added, distance of test panel from gun tip, wet film thickness, type of spray gun, traverse speed, air temperature, relative humidity, temperature of the test panel at the time of application, and the thickness values. These parameters help in troubleshooting, research, & development, ensuring regulatory compliance.
Tests Related to ASTM D823
ASTM D7091 is a test similar to ASTM D823. It is based on some nondestructive methods and offers guidelines for measuring the dry film thickness of coatings and evaluating their performance.
