Definition
A print color spreader is a laboratory instrument used to simulate the printing process and generate standardized color blocks. It produces a uniform color sample of the field area or dot area on the specified substrate material by precisely controlling the ink layer thickness and printing pressure. Its primary function is to provide a repeatable, comparable basis for physical color samples for quality control, color matching, and material testing in the printing industry.
Principle
The core working principle of a print color spreader is to simulate the mechanical action of lithographic or gravure printing. The instrument typically contains a precise squeegee system and an ink homogenization system. When working, the operator applies the quantitative ink to the uniform roller, distributes the ink evenly through the uniforming system, and then transfers the ink to the pre-installed printing plate or specific groove by the squeegee under constant pressure and speed, and finally embosses it on the surface of the substrate material. The key to the whole process is the closed-loop control of the thickness, pressure and speed of the ink layer, and the relationship can be approximately expressed as:Ek ∝ (F · v) / w, among themEkrepresents the thickness of the transferred ink layer,Ffor scraper pressure,vfor the scraping speed,wis the rheological characteristic parameter of the ink. This ensures a consistent color pattern every time the color is developed.
Measurement and evaluation methods
After the excellent sample is prepared using a printed color spreader, it needs to be combined with a spectral density meter or spectrophotometer for objective measurement. Common measurements include chromaticity value, ink layer density, and dot expansion. Chromaticity measurements are typically performed under standard illuminator D50 and 2° observer conditions, and CIELAB values are obtained to calculate chromatic aberration ΔE. Ink layer density measurement uses a specific color filter to evaluate the coloring power of the ink. For dot color samples, the dot area coverage can be calculated by instrumental measurement, and the printing characteristics can be analyzed compared with the theoretical values. All measurement methods refer to ISO 2846, ISO 12647 and other series of standards to ensure international comparability of data.
Main influencing factors
The accuracy and repeatability of color development results are affected by multiple factors. Instrument factors include the accuracy of the ink scraper, the stability of the pressure control, and the uniformity of the ink homogenization system. Material factors involve the viscosity, thixotropy, and coloring strength of the ink, as well as the smoothness, ink absorption, and whiteness of the substrate material. Environmental factors such as temperature and relative humidity in the laboratory can affect the rheology and drying speed of the ink. Operating factors include the amount of ink applied, the time it takes to sit before color development, and how clean the instrument is. The control of the system needs to take into account these variables.
Applications
Printed color spreaders have a wide range of uses in several industrial sectors. In packaging printing, it is used to evaluate the color performance and adhesion of inks on paper, plastic film, or metal foil. In the ink manufacturing industry, it is a key tool for developing new products, checking batch-to-batch consistency, and determining ink colorability. In printing enterprises, it can be used to establish printing characteristic curves and provide basic data for color management. In addition, it is also often used in scientific research institutions to study the printing suitability of new printing materials or environmentally friendly inks.
Key points to consider in selection
Selecting the right print color spreader requires a comprehensive evaluation based on specific application needs. Consider the type of instrument, such as whether it is suitable for lithographic or gravure inks. Examine its technical parameters, including adjustable pressure ranges, precision of scraping speeds, and maximum color spread. The construction material and durability of the instrument are related to the stability of long-term use. In terms of compatibility, it is necessary to confirm whether it supports commonly used standard test methods and the required substrate specifications. In addition, the convenience of operation, the complexity of maintenance, and the technical support and services provided by the supplier are also important decision-making bases. Users are advised to conduct sample testing before purchasing to verify the performance of the instrument under actual working conditions.