--- title: "Tubing Shore Hardness: Shore A vs Shore D Chart" canonical: "https://yuannaitube.com/tubing-shore-hardness/" language: "en-US" --- RESOURCES # Tubing Shore Hardness: Shore A vs Shore D Chart By [YUANNAI TUBE]() Published 2026-11-08Updated 2026-11-08 ![Clear coiled tubing, a black tube and a short translucent tube on a steel surface]() **Shore hardness** is the number that tubing makers, fitting makers and buyers use to describe how hard a polymer is. Two scales matter for tubing: **Shore A** for flexible materials such as polyurethane and **Shore D** for harder ones such as nylon and fluoropolymers. This page lists the hardness values on our own data sheets and explains how to read and write them, so a specification names the scale, the value and the test. **Quick answer.** Our **PU tubing** is listed at 98 ± 2 Shore A and our **polyether tubing** at 95 ± 2 Shore A. Our nylon and **fluoropolymer tubing** is listed on Shore D: PA6 75 ± 5, PA12 65 ± 5, FEP 55 ± 5 and PFA 60. A value is only meaningful with its scale letter, and values on different scales should not be converted into each other. ## Hardness of our tubing, from the data sheets These are the hardness lines printed on the technical data sheet of each family. Each is quoted on the scale the data sheet uses, so the numbers on the two scales are not a ranking against each other. | Tubing | Hardness on the data sheet | Scale | Data sheet | | --- | --- | --- | --- | | [PU tubing]() | 98 ± 2 | Shore A | [PU data sheet]() | | [Polyether tubing]() | 95 ± 2 | Shore A | [Polyether data sheet]() | | [PA6 nylon tubing]() | 75 ± 5 | Shore D | [PA6 data sheet]() | | [PA12 nylon tubing]() | 65 ± 5 | Shore D | [PA12 data sheet]() | | [FEP tubing]() | 55 ± 5 | Shore D | [FEP data sheet]() | | [PFA tubing]() | 60 | Shore D | [PFA data sheet]() | The data sheets for our PE, composite, flame-retardant and **recoil tubing** do not state a Shore hardness, so none is given here. The data sheets state the scale and the value; if your specification needs a reading time as well, ask for it with your quotation request. ## Shore A and Shore D: what each scale measures Both scales measure how far a spring-loaded indenter presses into the material, on a reading from 0 to 100 (Infinita Lab). The scales differ in the indenter and the spring, so a number from one scale cannot be compared directly with a number from the other. | | Shore A | Shore D | | --- | --- | --- | | Indenter | Truncated cone, 35°, 0.79 mm flat tip | Sharp cone, 30° | | Spring force (Rex Gauge) | 822 g | 10 lb | | Used for | Flexible rubbers and elastomers | Hard rubbers and plastics | | Typical tubing | Polyurethane | Nylon, fluoropolymers | The test is standardized as ASTM D2240, and the same kind of test is covered by ISO 868 and DIN ISO 7619-1. The indenter and force figures are from Infinita Lab and from CASRAI, which quotes Rex Gauge’s published gauge specifications; the use cases are from Smooth-On, which also notes that semi-rigid plastics can be measured on the high end of the Shore A scale and that Shore D covers hard rubbers, semi-rigid plastics and hard plastics. The “typical tubing” row is our own reading of our data sheets above. ## Five rules for reading and writing a hardness value 1. **Always write the scale.** “98” means nothing; “98 Shore A” does. 2. **Do not convert between scales.** The scales use different indenters and springs, and approximation charts exist but are not recommended for official specifications (Worldoftest, CASRAI). The scales do overlap: Smooth-On gives 95A as also 45D for one material. That is an example of overlap, not a conversion rule for tubing. 3. **Treat the ends of a scale with care.** CASRAI, summarizing Wikipedia, notes that results below 10 or above 90 on a scale are not to be trusted and the adjacent scale should be used. Our PU and polyether values (98 and 95) sit near the top of Shore A, so compare like with like and ask how a value was measured. 4. **State the reading time.** Readings may be taken instantaneously, within about one second of firm contact, or after a delay; sources differ, and the time should be reported (Infinita Lab, CASRAI). If two suppliers quote the same number, confirm they read at the same time. 5. **Do not use hardness as a flexibility rating.** **Wall thickness** and construction also decide how a tube bends, so give the **bend radius** from the model table as well. Compare for yourself on the [tubing size chart]() . ## How to put hardness in a tubing specification Write hardness only when a fitting or application needs it: the scale, the value or range, the test standard and, if it matters, the reading time. For example: “Hardness 95 ± 2 Shore A, ASTM D2240.” The full specification template, with the other fields, is in [how to specify tubing]() , and the terms are defined in the [tubing glossary]() . If you are choosing between PU grades, see [polyether vs polyester PU tubing]() ; for nylon against PU, the [PU vs nylon selection checklist]() . ![Cut sections of clear, blue, white and black tubing showing the bore and wall thickness]() Fig. 1: Illustrative cut sections of tubing in several colors. Hardness is measured on the material, and wall thickness and construction also decide how a tube bends. Illustrative image, not a product photograph. ## Shore hardness FAQ What is the difference between Shore A and Shore D? They use different indenters and springs. Shore A is used for flexible rubbers and elastomers, Shore D for hard rubbers and plastics. In our range, PU and **polyether tubing** are listed on Shore A, and nylon, FEP and **PFA tubing** on Shore D. What Shore hardness is PU tubing? Our **PU tubing** data sheet lists 98 ± 2 Shore A, and our **polyether tubing** data sheet lists 95 ± 2 Shore A. Can I convert Shore A to Shore D? Not for a specification. Approximation charts exist, but the scales measure hardness differently and sources advise against using a conversion for official specifications. Ask for the value on the scale your fitting maker or drawing uses. Does a higher Shore number mean a stiffer tube? Within one scale, a higher number means a harder material. How a tube bends also depends on **wall thickness** and construction, so use the **bend radius** in the model table for your size. Do I need to specify Shore hardness when I order tubing? Only if your fitting or application calls for it. In that case write the scale, the value or range and the test standard. Otherwise the model code and the data sheet already fix the material. ## Sources and scope - [Smooth-On, Durometer Shore Hardness Scale]() - [Infinita Lab, ASTM D2240 Shore Durometer Hardness Testing]() - [CASRAI, Durometer: Shore A vs D and How to Read It]() - [Worldoftest, Your Expert ASTM D2240 Durometer Guide]() - YUANNAI TUBE data sheets for PU, polyether, PA6, PA12, FEP and **PFA tubing**, linked in the table above. The scale descriptions come from these third-party pages and paraphrase ASTM D2240 rather than quoting it; use the current standard if you need its exact wording. The hardness values apply to the identified YUANNAI TUBE models and the conditions stated on their data sheets. Confirm the exact model and required evidence before ordering. Content review: [zhangkexin]() · Marketing Review scope: market information and document references. ## Tell us what your application needs. Send your dimensions, operating conditions and quantity. Let’s identify the right tubing for your project. [Request a Quote →]() ## Related tubing products ![Multi-Lumen Tubing]() [Specialty]() ### Multi-Lumen Tubing Custom multi-lumen (multi-bore, multi-core) tubing: twin and multi-line parallel lines for equipment integration. Lumen count, sizes, material and construction are agreed per drawing or sample. [View details →]() ![Antistatic PU Tubing]() [Specialty]() ### Antistatic PU Tubing Custom antistatic (static-dissipative) PU tubing for air and fluid lines near electronics. Resistance range, size and compound are agreed per project and confirmed on samples. [View details →]() ![Flame-Retardant Tubing]() [Specialty]() ### Flame-Retardant Tubing Flame-retardant tubing for air lines. 5 models from 2.5 x 4 mm to 8 x 12 mm. State the fire-performance standard your project requires. [View details →]() ![High-Pressure Composite Tubing]() [Composite]() ### High-Pressure Composite Tubing High-pressure composite tubing for pneumatic, lubrication, spraying and fluid-transfer lines. 28 models: V8 (PU + PA12) and V9 (polyether TPU + PA12). [View details →]()