Definition
An ISO wet film preparer is a laboratory tool used to prepare wet film coatings with a specific thickness on the surface of a leveled substrate. Its design adheres to relevant ISO specifications, ensuring consistent coating thickness and providing standardized samples for subsequent coating performance evaluation.
How it works:
The instrument is based on the principle of gap coating, with a precision-machined metal frame with a specific height of clearance at the bottom. When the instrument scrapes at a uniform rate on the surface of the substrate, the excess paint is scraped off, and the remaining paint fills the gaps and forms a uniform wet film on the substrate. Wet film thickness is determined by the gap height, and the relationship can be expressed as:
h=g
Among themhrepresents the thickness of the wet film,gIndicates the height of the preparer gap.
Measurement method
The preparer and substrate need to be cleaned before use. Place an appropriate amount of paint on the front of the substrate, hold the preparer steadily with both hands, and scrape the paint area at a constant speed at once. Check the continuity of the wet film immediately after scraping, and perform thickness verification or performance testing within the specified time. Thickness verification typically employs a wet film thickness gauge for multi-point measurements, ensuring thickness deviations within standard allowable ranges.
Influencing factors
Coating uniformity is affected by a variety of factors. Fluctuations in scraping speed can lead to uneven thickness distribution; Insufficient surface flatness of the substrate may cause local thickness deviation. Rheological properties of coatings, such as viscosity and thixotropy, affect the leveling and springback of the coating; Ambient temperature and humidity may change the volatilization rate and fluidity of the coating. Operator consistency is also a key factor in achieving reproducible results.
Applications:
This equipment is widely used in coating research and development and quality inspection to prepare test samples to evaluate the optical, mechanical and weather properties of coatings. In the automotive industry, it is used to prepare coating samples for adhesion and hardness testing; In the construction field, it is used to evaluate the hiding power and color stability of decorative coatings. In the electronics industry, it is used to prepare samples of functional coatings for electrical performance testing. In addition, it is often used in standard laboratories for coating comparison tests and certification tests.
Key points of selection
When selecting, the required wet film thickness range should be confirmed first, and common preparers are available in a variety of sizes from 25 microns to 1000 microns. The material should be corrosion-resistant and wear-resistant, and the edge accuracy should meet the requirements of relevant standards. Consider whether a modular design is required to accommodate different thickness requirements. Comfort and ease of cleaning are also practical considerations. It is recommended to choose products that comply with ISO standards and provide calibration certificates to ensure traceability of measurements.