In industrial production, hardness is a key indicator that defines material quality. For plastics, rubber, or coatings, controlling hardness optimizes performance, durability, and usability. The Shore hardness scale was established as an international standard system, offering an accurate evaluation method widely used across industries.
WHAT IS THE SHORE HARDNESS SCALE?
The Shore hardness scale measures the hardness of non-metallic materials. It reflects resistance to indentation when under force. Values range from 0 to 100. A higher value means a harder material, while a lower value means a softer one.
The scale is applied to a wide range of materials. Plastics, rubber, polyurethane, coatings, medical gels, and cosmetics can all be measured. With such flexibility, it has become an essential tool in both manufacturing and research.
COMMON SHORE HARDNESS SCALES
Shore 00 – for very soft materials
Shore 00 is designed for extremely soft materials. Gel, medical silicone, cosmetics, or foam are typical examples. Cosmetic gel usually reads around 20 Shore 00, while soft polyurethane foam is around 50 Shore 00. These values highlight high elasticity and deformation. The most common applications are in healthcare and personal care. Controlling softness ensures safety and comfort for users.
Shore A – for soft materials
Shore A is used for rubber, TPE, soft PU, and elastic coatings. It is the most common scale since many materials fall within this range. Natural rubber is around 60A, while PU sports shoes are about 70A. In coatings, Shore A evaluates polyurethane elastomer layers, often 80–90A. These values show strong impact resistance and abrasion performance.
Shore D – for hard materials
Shore D applies to engineering plastics, epoxy, and rigid polyurethane. ABS plastic is typically 70D, while industrial epoxy can reach 85D. Rigid polyurethane coatings usually measure 70D–90D. This scale allows manufacturers to control durability and crack resistance, even under harsh conditions.
Shore O and other variants
Besides the three main scales, there is Shore O and variants like AO or AM. These are less common in industry and mostly seen in research. They bridge ranges between Shore A and Shore 00. Though rarely applied in mass production, they add detail to classification. They remain useful in laboratories and material development.
INTERNATIONAL SHORE HARDNESS STANDARDS
ASTM D2240 (USA)
ASTM D2240 is the most widely used Shore hardness standard. It applies to rubber, elastomers, thermoplastics, rigid plastics, and gels. Samples must be at least 6 mm thick. Test conditions are 23 ± 2°C and 50 ± 5% RH. With proven reliability, ASTM D2240 is recognized worldwide as the reference standard. Many industries rely on it for quality control.
ISO 868 (International)
ISO 868 was published by the International Organization for Standardization. It is equivalent to ASTM D2240 but more globally applied. ISO 868 allows multiple scales, including A, D, 00, AO, and AM. This flexibility supports both research and production. On a global level, ISO 868 helps manufacturers meet requirements across many markets, which is a strong advantage for exports.
DIN 53505 (Germany)
DIN 53505 is the German standard focused on rubber and elastomers. It is similar to ISO 868 but widely adopted in Europe. With long-standing credibility, DIN 53505 remains important in the EU market, especially in rubber manufacturing.
HOW TO MEASURE AND COMPARE SHORE HARDNESS
How to measure hardness
Shore hardness is measured with a durometer. The indenter presses into the sample under a set force, and the reading is displayed on the scale. The harder the material, the higher the reading.
Samples must be thick enough, at least 6 mm. If thinner, several layers are stacked. Testing should avoid edges or curved areas. Standard conditions are 23 ± 2°C and 50 ± 5% RH. In practice, an eraser measures around 40A, natural rubber around 60A, PU sports shoes about 70A, ABS plastic 70D, and industrial epoxy 85D.
Comparing Shore hardness scales
Each Shore scale has unique characteristics and serves specific purposes. Shore 00 is for very soft materials like gel and silicone. Shore A fits soft to medium materials such as rubber, TPE, and elastic coatings. Shore D applies to hard materials like engineering plastics, epoxy, and rigid PU.
This division makes the system both comprehensive and flexible. Companies can select the right scale based on the nature and requirements of their materials. This ensures effective quality control and reduces risks in production and application.
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