Definition
An ink hand spreader is a laboratory testing instrument used to evaluate the flow and elongation characteristics of inks. It simulates manual color exhibition operations, evenly unfolds the quantified ink under specific conditions, forming a thickness gradient ink film, so that its color, gloss, coverage and leveling and other performance indicators can be observed or measured later. The instrument plays an important role in ink research and development, quality control, and printing process suitability testing.
Principle
The core working principle of the ink hand spreader is based on mechanical scraping. The instrument typically features an adjustable scraper or applicator with a sophisticated gap control structure at the bottom. When the dosing ink is placed on a substrate (such as paper, plastic film, or metal foil), the scraper scrapes the ink at a constant speed and pressure, forming a film that transitions from thick to thin on the surface of the substrate. Ink film thicknesshGap with the scraperdand the rheological properties of ink, which can be approximately expressed ash ≈ k · d, among themkis the coefficient related to the ink viscosity, scraping speed and other factors. By observing the performance of ink films in different thickness areas, the suitability of inks can be systematically evaluated.
Measurement method
The standard process for measuring with ink spreaders typically follows relevant industry standards (e.g., ASTM D1210, ISO 8789, etc.). First, the selected substrate is flattened to the base of the instrument. Subsequently, a standard volume of ink sample is placed at the beginning of the substrate. Start the instrument so that the scraper scrapes at a uniform speed at a specified speed (e.g., 10 cm/s) to form a gradient ink film. After the ink film dries under standard temperature and humidity conditions, different areas of the ink film are evaluated visually or by instruments (such as colorimeter, gloss meter, film thickness meter). Common measurements include color consistency, gloss variations, coverage critical thickness, and where leveling defects (e.g., stripes, orange peel) appear.
Influencing factors
The measurement results of ink hand development meters are affected by multiple factors. Instrumental factors include scraper accuracy, gap repeatability, scraping speed stability, and base flatness. Operating factors include the accuracy of ink sampling, ambient temperature and humidity control, and drying conditions. The material factors involve the rheological properties of the ink itself, such as viscosity, thixotropy, and yield value, as well as the surface energy, roughness and absorption of the substrate. The combination of these factors determines the quality of the formation of the ink film and the reproducibility of the test results, so standardized operation and environmental control are the prerequisites for obtaining reliable data.
Application:
Ink hand spreader is widely used in printing, packaging, coatings, ink manufacturing and other industries. In the R&D phase, it is used to screen pigments, resins, and solvent formulations to optimize the printability of inks. In the quality control process, it is used to compare the color intensity, color development effect and coverage consistency of different batches of inks. In print process adaptation, it helps determine the ink viscosity and drying characteristics required for a particular press and substrate. It is also used to evaluate the coating uniformity and performance threshold of functional inks (e.g., conductive inks, security inks).
Selection
When choosing an ink hand spreader, you need to consider multiple technical parameters and application requirements. The core parameters include the scraping width (commonly 150mm to 300mm), the clearance adjustment range and accuracy (usually in the micron range), and the scraping speed range and control method. Instrument materials should be corrosion-resistant and easy to clean, and critical moving parts should ensure smooth and repeatable long-term operation. According to the requirements of the test standard, it can be equipped with a thermostatic base or an automatic coating module. For high-precision R&D applications, it is recommended to choose a model with digital control and data logging functions; For routine quality inspection, models with easy operation and reasonable maintenance costs are more suitable. The final selection should be based on the actual ink type, substrate range, and the standard specifications followed.