Toyota TSH 1539G Paint Film Hardness

The “Toyota TSH 1539G Paint Film Hardness” standard, developed by the Toyota vehicle company, describes a test method for determining the resistance of vehicle coatings to scratches.

If a coating does not dry or cure properly, this can affect the performance of the paint, causing defects, poor adhesion and premature coating failure. Therefore, it is necessary to test the hardness of the coating. This test determines how well the coating has cured. Generally, the harder the coating, the more complete the cure and the better the overall performance of the coating.

One of the most common methods of determining coating hardness is the pencil hardness test, in which a pencil of known hardness is pressed onto the coating at a specified angle under a constant force.

The pencil hardness is increased from B (soft) to HB (medium) to H (hard) until the coating is scratched. Alternatively, depending on the testing method, start with the hardest pencil and then decrease the pencil hardness until the coating is not scratched.

This fast and economical method is used not only by coating manufacturers during development work and as an indicator of coating performance, but also as a field test during post-application inspection.

The pencil hardness test consists of 14 pencils (grades 6H to 6B), two special sharpeners, and an abrasive paper block to prepare the pencil for testing. Alternatively, some standards use a specially designed tester. A set of 14 pencils also includes a calibration block of a predefined size to prepare the tester.

The scratch method is a destructive test and will damage the coating, so the use of test panels is recommended when testing using this method.

Film hardness is defined as the property of a paint film to resist and resist impact or mechanical stress such as scratching, impact or penetration by a hard object. In other words, film hardness is the resistance of a film to damage or deformation. For a coating on a hard substrate, the hardness or resistance to deformation increases with a decrease in film thickness. During the process, all parameters such as curing time, application conditions and other relevant parameters are kept constant. This means that the systems, i.e. the substrate and the coating, are more resistant to damage. Therefore, the hardness is better with thin film thickness compared to thicker ones.

Key benefits of rigid films include:

• It increases durability and also protects the substrate and itself by protecting it from abrasion and other mechanical stresses.
• It offers excellent barrier properties against external factors, including moisture, chemicals, temperature, dust and dirt.
• It can add other functional performance properties. This depends on the thickness of the film. These properties include electrical, optical, crack and corrosion resistance.

Factors affecting film hardness are:

• Optimum curing of thin film coating or paint. Optimum curing of the film includes factors such as drying time, evaporation rate of solvents and optimum film thickness. Optimization of all these factors results in excellent film hardness.
• Application process and conditions. This includes choosing the right film coating process. It ensures uniform film thickness and conditions. For example, drying, humidity and temperature.
• The nature of the substrate. The nature of the substrate is related to factors such as substrate surface morphology, surface energy, coating compatibility and thermal expansion of the coating material. If the substrate is not stable, it will lead to insufficient adhesion. In addition, improper and inadequate substrate preparation can also hinder film hardness.
• The composition or recipe of the coating. This plays a critical role in film hardness. The desired film hardness of the coating is a result of factors such as polymer selection, the presence of crosslinkers, the presence of nanoemulsions or nanomaterials such as silica, or other hardness-inducing components.

Among the numerous tests, measurements, analyses and evaluation studies carried out for businesses in various sectors, our organization also provides testing services defined in the “Toyota TSH 1539G Paint Film Hardness” standard with its trained and expert staff and advanced technological equipment.