The ISO 2815 Paints and varnishes - Buchholz indentation test standard, developed by the International Organization for Standardization (ISO), describes the method for performing indentation tests on single-layer or multi-layer paints, varnishes, or related product systems using a Buchholz indenter. The length of the resulting indentation indicates the permanent deformation of the coating. This indentation test is not suitable for products containing strong plasticizers.
Indentation tests, like other physical tests on paints, yield results that can be affected by time, temperature, and humidity; therefore, comparable results can only be obtained when the test is performed under well-defined conditions. Since indentation depth depends on film thickness, the result obtained for indentation length is only valid when the coating thickness exceeds a certain minimum value.
In principle, an indentation end of the specified size and shape is applied to the coating under defined conditions. The indentation length is measured in millimeters.
In short, this standard is an international standard that specifies a method for evaluating the indentation hardness (or resistance to permanent deformation) of paint coatings, varnishes, and related products.
This standard describes a repeatable indentation test using a Buchholz indentor (a specially weighted tool with a sharp, hardened metal wheel or chisel-shaped edge). This test measures the length of the indentation remaining in the coating after a controlled load has been applied for a specified period of time.
This method evaluates single-layer or multi-layer paint, varnish, or similar product systems. It provides information about mechanical properties such as hardness and resistance to deformation under local pressure (useful for quality control, product comparison, and specification compliance in the coatings industries).
However, this method is not suitable for coatings containing strong plasticizers (these may exhibit excessive flow or recovery, leading to unreliable results). Furthermore, the results depend on the film thickness: indentation is only valid when the dry coating thickness exceeds the minimum value specified in the standard (to avoid substrate effect). Meanwhile, test results are sensitive to environmental conditions (time after application, temperature, humidity), therefore tests must be conducted under tightly controlled conditions (typically 23 degrees plus/minus 2 degrees temperature and 50 percent plus/minus 5 percent relative humidity).
During testing, a flat test panel with the coating applied and fully cured/dried is prepared. The dry film thickness is measured (according to ISO 2808 standard). The panel is placed on a solid, horizontal surface. A Buchholz indenter is used. A constant load (usually 500 g) is applied through the indenter tip for a specific time (e.g., 30 seconds). The load is removed, and the length of the resulting indentation is immediately measured (typically under a microscope or magnifying device). The average indentation length (in mm) is reported, or converted to an indentation resistance value (optional).
The standards related to this method are as follows:
The Buchholz test is widely used in paint laboratories and quality assurance for architectural paints, industrial coatings, automotive coatings, and protective systems. Specialized Buchholz indentation testing equipment is required to perform this test according to the standard.
This method is one of several indentation/hardness tests used for coatings (others include pencil hardness, Persoz pendulum, or nano-indentation), but the Buchholz method remains popular due to its simplicity, repeatability, and low equipment cost.
In short, the Buchholz indentation test is an important method in the coatings industry because it provides a simple, repeatable, and standardized way to evaluate the indentation hardness (or resistance to permanent deformation) of paint films, varnishes, and similar coatings. This method is considered important for the following reasons:
It is particularly valuable in the following sectors:
In short, a coating may initially look perfect, but it can fail if it's too soft to withstand daily pressure. The Buchholz method helps catch this early, reducing rejected products, warranty claims, and performance failures.
For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services compliant with the ISO 2815 standard.
To get an appointment, to get more detailed information or to request an evaluation, you can ask us to fill in our form and reach you.
