Definition
The manual ink spreader wheel is a laboratory testing instrument used in the printing and related industries, mainly used to simulate the printing process and prepare a uniform layer of ink or coating sample. By manual operation, the instrument creates a controllable thickness of coating on a specific substrate for subsequent evaluation of color, gloss, adhesion, and other properties.
Principle
The core working principle of the manual ink spreader wheel is based on mechanical rotation and pressure control. The instrument typically consists of a base, a rotating handle, and an adjustable scraper. During operation, the ink or coating to be tested is placed on the substrate, and the color spreader is driven by manual rotation to make the squeegee scrape the sample at a constant pressure and speed, so as to form a film layer of uniform thickness. The film thickness control can be achieved by adjusting the squeegee pressure or using molds with different clearances, and the basic relationship can be expressed as: film thickness is related to the squeegee gap and the rheological properties of the material. The formula is expressed as:h ≈ k × G, among themhrepresentative film thickness,Gfor the scraper gap,kis the coefficient related to the viscosity of the material.
Measurement method
When using a manual ink spreader wheel for sample preparation, standardized steps are followed. First, select the appropriate substrate (such as paper, plastic film, or metal foil) and secure it to the base of the color spreader. Subsequently, a sample of the quantitative ink is taken and placed on the front end of the substrate, ensuring that the squeegee is parallel to the surface of the substrate. The operator rotates the handle at a uniform speed to scrape the squeegee over the sample to create a continuous layer. The prepared samples are dried in a standard environment and then tested according to the target parameters (e.g., chromaticity, masking power). This method typically refers to industry standards such as ISO 2834, ASTM D5005, etc., to ensure comparable results.
Influencing factors
The test results of a manual ink spreader are influenced by a variety of factors. The consistency of the operation technique is directly related to the uniformity of the film layer, and the uneven rotation speed may lead to thickness fluctuations. Environmental conditions such as temperature and humidity can affect ink rheology, which in turn changes color development. The scraper state (e.g., degree of wear) and the surface properties of the substrate (e.g., flatness, absorbency) also play a role in film formation. In addition, the viscosity, solids content, and dispersibility of the ink itself are key variables that need to be controlled during testing.
Applications
Manual ink spreader wheels are widely used in the printing, coating, ink manufacturing and packaging materials industries. In the printing field, it is used for ink color proofing and print suitability evaluation. The coating industry uses this instrument to test coating coverage and leveling. In addition, it can be used in the development and quality control of substrates such as paper, plastics, and ceramics to simulate the coating process and assist in optimizing process parameters.
Selection considerations
When choosing a manual ink spreader, it is necessary to consider the actual needs comprehensively. The material of the instrument should be corrosion-resistant and stable, such as stainless steel structure to ensure long-term accuracy. The squeegee adjustment range needs to match common film thickness requirements, usually covering 0-100 microns. Fixtures that are compatible with a wide range of substrate sizes and types increase suitability. Operating comfort, such as the ergonomic design of the handle, helps reduce human error. At the same time, whether the instrument is easy to clean and maintain is also a practical factor. It is recommended to refer to relevant industry standards (such as ISO or ASTM) to ensure that the instrument's functionality meets the test specifications.