Hardness SHORE

Shore durometer are based on international standards for the hardness measurement of rubber, plastics and other non-metallic materials (ISO, ASTM, DIN, BS, NFT etc.).

Hardness is the resistance against the indentation of a known geometrical indentor with determined force into a sample. The indentation depth is measured and displayed analogically or digitally.

The indentor is 2.5 mm away from the contact surface at zero durometer reading. Therefore you can only measure samples with a thickness of 6 mm or more (durometer A) or you can stack 3 samples with 2 mm thickness each to 6 mm total.

If the samples are thinner than the recommended thickness you are measuring the hardness of the underlying surface (support table or workbench). This will give a false reading due to the "anvil effect".

Shore TYPE	Main spring	Contact force	Indentor shape	Measuring way	Material thickness	Measuring range	Norm	Application
A	8,065 N 822 gramme (100 Shore)	12,5 N	35°	2,5 mm	> 6 mm 2+2+2 = 6 mm	10 - 90 10 -90 < 20 Shore D	ISO 7619-1 ASTM D 2240 IS0 868	Soft rubber, pastics & elastomers.
D	44,50 N 4536 gramme (100 Shore)	50,0 N	30°	2,5 mm	> 6 mm 2+2+2 = 6 mm	30 - 90 10 - 90 > 90 Shore A	ISO 7619-1 ASTM D 2240 IS0 868	Hard rubber, thermoplsatics
AO	8,065 N 822 gramme (100 Shore	1000 g	Ø 5 mm	2,5 mm	> 6 mm	< 20 Shore A	ISO 7619-1	Foams, steering wheel, upholstery of automotive interiors
B	8,065 N 822 gramme (100 Shore)	12,5 N	30°	2,5 mm	> 6 mm	10 - 90	ASTM D 2240	Harder elastomers and plastics that shore A
C	44,50 N 4536 gramme (100 Shore)	50,0 N	35°	2,5 mm	> 6 mm	10 - 90	ASTM D 2240	Medium hard elastomers
DO	44,50 N 4536 gramme (100 Shore)	50,0 N	3/32"	2,5 mm	> 6 mm	10 - 90	ASTM D 2240	Dense granular material, textile winding
O	8,065 N 822 gramme (100 Shore)	12,5 N	3/32"	2,5 mm	> 6 mm	10 - 90	ASTM D 2240	Very soft elastomers, textile winding bellow  20 Shore A.
OO	1,10853N 113 gramme (100 Shore)	3,924 N	3/32"	2,5 mm	> 6 mm	10 - 90	ASTM D 2240	Ligth foams, sponge rubber gels, human tissue.
OOO	1,10853N 113 gramme (100 Shore)		1/2"	2,5 mm	> 6 mm	10 - 90	ASTM D 2240	Gels, foam and rubber foam very soft
M			30°	1,25 mm	>1.27 mm		ASTM D 2240	Thin material
RR	13.832N 1410 gramme (100 Shore)		1/2"				no norm	Fiber panels, artificial brick
CF	89 N 9072 gramme (100 Shore		1/2"				no norm	Foam padding
Barcol			26° Ø 0.157	0,76 mm		0 - 100	ASTM D 2583	Composite, plastic reinforced fiberglass, thermoplastic acrylic glass, resopal, vinyl, acetate of cellulose, Tin, aluminum

Creep: if the durometer is maintained with constant pressure on the sample, the specified hardness will decrease with time: the penetrator tends to continue to penetrate into the material. This phenomenon called creep varies from material to another, but requires more rigour to the extent that it is important: measurement of the hardness after a well-defined time after the application of the load interval, maximum indicator...

Example: measurement time according to ASTM D 2240 (durometer A): 1 second, ISO 7619-1, Shore A measurement time: 3 seconds

Indicative table, do not use as conversion table

Hand test: the pressure force of the durometer on the sample is produced by hand (mass durometer + hand force). Subjective measurement errors, caused by incorrect contact pressure or non-vertical measurements, are possible. This means that the measured values ​​vary more. A test with a test bench eliminates these errors => better precision/reproducibility