ASTM D395 Complete Guide: Compression Set of Rubber, Methods A, B and C, Fixtures and Calculations

ASTM D395 is the standard compression set test for rubber: a disc is squeezed by a fixed amount or a fixed force, held at temperature for 22 or 70 hours, released, and the permanent loss of thickness is reported as a percentage. It is the single most important number on most seal, gasket and O-ring specifications, because a compound that takes a set stops pushing back against the mating surface, and a seal that stops pushing back leaks. The test looks simple, but the result moves with the method (A, B or C), the specimen type, plied versus solid discs, spacer height, oven temperature, how fast the fixture is opened and how long the specimen recovers. This complete guide covers the three D395 methods, Type 1 and Type 2 specimens and their dimensions, specimen cutting and conditioning, Method B fixtures and spacers, ovens and environmental chambers, where a testing machine fits (Method A load application and the related D575 and D412 tests on a Mark-10 or Galdabini frame), the calculations with worked examples, typical values, D395 vs. ISO 815-1, troubleshooting and a full FAQ.

D395 is a fixture-and-oven test, not a tensile-machine test, and we will be clear about where test machines, grips and extensometers do and do not belong. For the fixture itself, with downloads and specifications, see our ASTM D395 compression set fixture page.

ASTM D395 at a glance

• Full title: Standard Test Methods for Rubber Property, Compression Set (current edition D395-18, reapproved 2025).

• What it measures: the permanent deformation that remains after a rubber specimen is held under compression for a set time at a set temperature and then allowed to recover. Lower is better.

• Methods: A constant force in air (1.8 kN, about 400 lbf); B constant deflection in air (about 25 % compression using spacer bars); C constant deflection in air considering material hardness. Method B applies unless a specification says otherwise.

• Specimens: Type 1 disc 29.0 ± 0.5 mm diameter × 12.5 ± 0.5 mm thick (Methods A and B); Type 2 disc 13.0 ± 0.2 mm × 6.0 ± 0.2 mm (Method B). Plied discs are allowed (up to 7 plies for Type 1, 4 for Type 2).

• Spacer bars (Method B): about 9.5 mm for Type 1 and 4.5 mm for Type 2, giving roughly 25 % compression.

• Time and temperature: 22 h or 70 h are the standard periods; temperature comes from the material specification, usually one of the standard test temperatures such as 70, 100, 125, 150 or 175 °C.

• Recovery: 30 minutes at standard laboratory temperature on a poor heat conductor such as wood, then measure thickness.

• Results: Method A: CA = (t0 − ti) ÷ t0 × 100. Method B: CB = (t0 − ti) ÷ (t0 − tn) × 100.

• Limit: Method B is not suitable for vulcanizates harder than 90 IRHD.

• Typical equipment: a Method B compression set fixture with chromium-plated plates and spacers, an air-circulating aging oven, a rotating cutting die, and a dial thickness gauge.

What compression set measures and who uses it

A seal works by being squeezed. The rubber pushes back on the gland and the mating surface, and that contact stress keeps fluid in. Over time, and much faster at high temperature, the polymer network relaxes and new crosslinks form in the compressed shape, so when the squeeze is removed the rubber no longer returns to its original height. Compression set measures that loss. A compound with 15 % set has given up 15 % of the squeeze it was asked to hold; one with 60 % has given up most of it.

• O-rings, gaskets and seals: compression set is in almost every ASTM D2000 line call-out, in O-ring specifications through ASTM D1414, and in automotive, aerospace, fluid-power and appliance seal specifications.

• Vibration mounts and bumpers: mounts that take a set change height and stiffness, so set is a key acceptance property.

• Sponge and expanded rubber: ASTM D1056 uses a modified D395 Method B at 50 % deflection for its B suffix.

• Compound development and QC: compression set is very sensitive to the cure system and state of cure, so it is a quick check on under-cure, wrong cure package or contamination.

D395 is intended for static compression in air, usually at elevated temperature. It does not simulate fluid immersion, dynamic loading or the exact geometry of a gland, so it ranks compounds rather than predicting the life of a specific seal.

Methods A, B and C explained

Method A: constant force

A Type 1 disc is loaded with a constant force of 1.8 kN (about 400 lbf) in a calibrated spring-loaded compression device, held for the test period at temperature, released and recovered for 30 minutes. Because the force is fixed, a soft compound deflects much more than a hard one, and the result is expressed as a percentage of the original thickness: CA = (t0 − ti) ÷ t0 × 100. Method A suits products that see a fixed load in service, such as machinery mounts. It is less widely used than Method B and needs a calibrated spring device, so check that your specification actually calls for it.

Method B: constant deflection

The disc is compressed between flat, polished plates to the height of steel spacer bars, about 25 % compression, held for the test period at temperature, removed from the fixture and recovered for 30 minutes. The result is expressed as a percentage of the deflection applied: CB = (t0 − ti) ÷ (t0 − tn) × 100. A compound that does not recover at all scores 100 %; one that fully recovers scores 0 %. Method B is the default in D395 and in nearly every specification, and it is the method our compression set fixture is built for.

Method C: constant deflection considering hardness

Method C is a constant-deflection test in air in which the compression depends on the hardness of the material, the approach also used by ISO 815-1, where harder compounds are compressed less. It gives a constant-deflection route for compounds where 25 % compression is impractical, including materials harder than the 90 IRHD limit of Method B. It appears in recent editions only; check the current edition for its deflections, specimen and recovery requirements before you set up a Method C program.

Which method should you use?

• Method B unless a specification says otherwise. It is the default and the basis of nearly all published data.

• Method A only when a specification requires constant-force set, typically for mounts and pads under dead load.

• Method C when the specification calls for it, or for hard compounds above 90 IRHD.

• Never compare Method A and Method B results. They use different bases, and Method A values are numerically much smaller.

ASTM D395 specimens: Type 1 and Type 2 discs

• Type 1: 29.0 ± 0.5 mm (1.14 ± 0.02 in) diameter and 12.5 ± 0.5 mm (0.49 ± 0.02 in) thick. Used for Methods A and B, and the same disc used by ASTM D575 compression-deflection, so both tests can come from one slab.

• Type 2: 13.0 ± 0.2 mm (0.51 ± 0.01 in) diameter and 6.0 ± 0.2 mm (0.24 ± 0.01 in) thick. Method B only. Uses less material and fits more discs in each fixture and oven.

• Molded or cut: specimens can be molded in a button mold or cut from a laboratory slab. Equal cure time and temperature do not give equal state of cure in a thick button and a thin slab, so molded and cut specimens are not interchangeable.

• Plied specimens: discs cut from thinner sheet can be stacked, without cement, to the required height: up to 7 plies for Type 1 and 4 for Type 2. Plied results can differ from solid discs, especially if air is trapped between plies, so compare plied only with plied.

• Product specimens: for parts too thin or too small, the product specification defines the specimen. O-rings are tested under ASTM D1414 using cut sections, and sponge under D1056.

• Number of specimens: duplicate specimens with the average reported, or triplicate with the median reported, depending on the option chosen.

Cutting discs

Thick rubber cannot be die-cut cleanly with a flat press stroke: the edge cups inward and the faces are no longer parallel. D395 discs are cut with a rotating hollow die in a drill press, lubricated with a soap solution, with light feed pressure, at least 13 mm from the edge of the slab. Keep the die sharp and check that each disc has flat, parallel faces and square edges. Thicker product sections can be reduced by cutting and buffing to height.

Our flat cutting dies and arbor presses are the right tools for the dumbbell and tear specimens of D412 and D624 that a rubber lab runs on the same compounds, not for thick compression set discs. The video below shows the difference between hardened and ribbon steel dies for those flat specimens.

Conditioning

• Allow vulcanized specimens to rest for at least 24 hours after cure before testing, and test within the maximum storage time your edition allows (60 days in older editions).

• Let buffed specimens rest for at least 30 minutes before cutting.

• Condition for at least 3 hours at 23 ± 2 °C before measuring the original thickness.

• Moisture-sensitive compounds need at least 24 hours at 50 ± 5 % relative humidity.

• Measure the original thickness t0 at the centre of each disc, at standard laboratory temperature, with a dial gauge meeting ASTM D3767.

Apparatus: Method B fixture, spacers and plates

A Method B compression device is two or three flat steel plates held together by bolts, with spacer bars between the plates that set the compressed height. Specimens sit between the plates clear of the spacers and bolts. The device controls the result as much as the rubber does, so every part of it matters.

• Plates: rigid, flat and parallel, with chromium-plated, polished faces so the rubber can spread without sticking and the faces do not corrode in the oven. A plate that bows under the bolt load compresses the middle specimens less than the outer ones.

• Spacer bars: about 9.5 mm for Type 1 and 4.5 mm for Type 2, made to close tolerance and checked periodically. On a Type 1 disc the applied deflection is only about 3 mm, so a spacer 0.1 mm too thick reduces it by about 3 % of its value and shifts the result.

• Three-plate designs hold two layers of specimens in one fixture and save oven space.

• Lubrication: check whether your edition and specification allow a thin film of lubricant that does not attack the rubber on the plate faces; if you use one, report it, and use it consistently.

• Bolts: tighten evenly in a crossing pattern until the plates seat on the spacers all round, and check that no spacer can rotate.

• Specimen placement: keep discs well clear of the spacers and of each other, because the rubber bulges as it compresses.

Our ASTM D395 compression set fixture page shows the Method B fixture, and our wider range is on the compression fixtures and compression platens pages. For Method A, contact us with your specification.

Ovens vs. environmental chambers

The heat in a D395 test is applied for 22 or 70 hours, often longer, with the specimen locked in a fixture. That is a job for an aging oven, not for a chamber on a testing machine.

• Aging oven: an air-circulating laboratory oven of the type used for ASTM D573 heat aging, holding the test temperature uniformly and with enough capacity for several fixtures. Put the assembled fixture in the oven within 2 hours of assembly, and do not age different compounds that can contaminate each other in the same oven.

• Test temperature: from the material specification, usually one of the standard temperatures of ASTM D1349. Common choices are 70 °C for natural rubber and SBR, 100 °C for NBR and CR, 125 to 150 °C for EPDM and HNBR, 175 °C for silicone and 200 °C for FKM.

• Low-temperature compression set: set at sub-zero temperatures is a different method, ASTM D1229, with its own cold box and recovery procedure.

• Environmental chambers on a testing machine: these are for tests run on the frame at temperature, such as D575 compression-deflection, D412 tensile and D624 tear. Our environmental chambers run from −80 to +280 °C. Tying up a frame and chamber for 70 hours to age a fixture is poor use of both.

For sizing a chamber for the frame-based tests, see the temperature chamber buyer's guide.

Do you need a testing machine for ASTM D395?

For Method B, no. The deflection is set by the spacers and the bolts, the heat comes from an oven, and the measurement is a thickness gauge. A testing machine adds nothing to a Method B result, so do not buy one for that purpose.

A testing machine does earn its place in a D395 lab in three ways:

• Method A load application and verification: the 1.8 kN force must be known. A compression frame with platens is a practical way to check the force-deflection of the spring device, and some labs use a frame to apply and lock the load. Check what your edition allows for loading the device.

• ASTM D575 compression-deflection: stiffness of the same Type 1 disc at 12 ± 3 mm/min, either the force at a specified deflection or the deflection at a specified force. This is a true testing-machine test and the natural partner of D395.

• ASTM D412 tensile and ASTM D624 tear: almost every lab that runs D395 also certifies tensile, elongation and tear on the same compounds, and those run on a tensile frame with grips.

Mark-10 tensile testers: basic and QC rubber testing

A Mark-10 motorized frame covers the force range of rubber QC well. Because Method A needs 1.8 kN (about 405 lbf), choose at least a 500 lbF frame if you want to apply or verify that load:

• 500 lb (F505): 500 lbF (about 2.2 kN) and 18 in (457 mm) of travel. Enough for the 1.8 kN Method A load and for D575 on most compounds. For D412 and D624 at 500 mm/min, order the extended speed range option (up to 45 in/min, 1,100 mm/min); note that the F505 capacity drops to 300 lbF above 24 in/min.

• 750 lb (F755) and 1,500 lb (F1505): 32 in (813 mm) of travel and 10 to 600 mm/min as standard, which covers the 12 mm/min of D575 and the 500 mm/min of D412 and D624 without options, plus margin for hard compounds in compression. The best Mark-10 choice for a rubber QC lab.

• 100 lb (F105) and 300 lb (F305): fine for D412 and D624 on soft compounds, but below the 1.8 kN Method A load.

• All F-series frames hold speed to ±0.2 % and sample load at 5,000 Hz.

Compare the two machine families in Mark-10 test frame vs. universal testing machine.

Galdabini universal testing machines: advanced rubber labs

For compound development and certification labs that run D395 alongside D575, D412, D624 and D1414, a Galdabini benchtop universal testing machine is the better fit:

• 5 kN Quasar: a dual-column frame with 175 mm of column clearance for compression platens, grips and an environmental chamber. It covers D575 on almost any solid compound and the full D412 and D624 program.

• 10 kN Quasar: extra compression capacity for hard compounds, larger product samples and mounts.

• 2.5 kN Quasar: single column, up to 1,000 mm/min and 1 m of stroke, ideal for high-elongation D412 and D624 tear, with less compression headroom.

With UTM software you can store D575 cyclic methods, D412 and D624 methods and Method A spring checks on one frame, with reports in one format. See the universal testing machine buyer's guide.

Fixtures and grips for the rest of the rubber lab

D395 itself uses no grips. The fixtures that matter are the compression set device and, for the related tests on a frame, compression platens and rubber grips:

• ASTM D395 compression set fixture: plates, spacers and bolts for Method B, Type 1 and Type 2 discs.

• Compression platens: flat, parallel platens for D575 compression-deflection and for checking Method A springs. Use a spherically seated platen when the specimen faces are not perfectly parallel. D575 specifies fine abrasive paper on the platens to stop slip, so do not lubricate them for that test.

• Pneumatic grips and roller grips: self-tightening or constant-pressure grips for D412 dumbbells and D624 tear specimens, which pull out of ordinary grips as the rubber thins.

• ASTM D1414 O-ring fixture: spools for O-ring tensile testing; O-ring compression set uses cut sections in a D395 Method B fixture.

Do you need an extensometer for ASTM D395?

No. Compression set is calculated from two thickness readings taken with a dial gauge before and after the test. No strain is measured during the test, and no extensometer, compressometer or video system is involved. Do not buy one for D395.

Strain measurement belongs to the related tests in the same lab:

• ASTM D412 elongation: must be measured on the bench marks, not from the crosshead, and a non-contact video extensometer follows soft rubber to break without touching it. The UGC-VE-2109 gives a 220 mm field of view at ISO 9513 Class 0.5 and 440 mm at Class 1, and the UGC-VE-2116 extends that to 330 mm and 660 mm. Long-travel contact arms such as our XL extensometers are the lower-cost alternative at room temperature.

• ASTM D575 deflection: usually taken from crosshead travel with compliance correction; a compressometer helps on thin plied stacks.

See types of extensometers and our ASTM D412 complete guide.

ASTM D395 Method B procedure, step by step

• Step 1: Cut or mold at least two (or three) Type 1 or Type 2 discs per compound, check that faces are flat and parallel, and condition them for at least 3 hours at 23 ± 2 °C.

• Step 2: Measure the original thickness t0 at the centre of each disc with a D3767 dial gauge, to 0.01 mm.

• Step 3: Check the spacer height tn and confirm the deflection: (t0 − tn) ÷ t0 should be close to 25 %.

• Step 4: Place the discs between the clean plates, clear of the spacers and each other, with spacers on each side, and tighten the bolts evenly until the plates seat on the spacers.

• Step 5: Put the assembled fixture in the oven, preheated to the test temperature, within 2 hours of assembly. Start timing.

• Step 6: At the end of 22 h or 70 h, remove the fixture, open it promptly and remove the discs. Do not let them cool in the compressed state.

• Step 7: Place the discs on a poor heat conductor such as a wooden bench and let them recover for 30 minutes at standard laboratory temperature.

• Step 8: Measure the final thickness ti at the centre, calculate CB for each disc, and report the average of two or the median of three.

Method A in brief

For Method A, measure t0 on Type 1 discs, load each disc to 1.8 kN in the calibrated spring device, age at temperature for the test period, release, recover for 30 minutes on a poor heat conductor, measure ti and calculate CA on the original thickness.

Calculations and worked examples

• Method A: CA = (t0 − ti) ÷ t0 × 100, where t0 is original thickness and ti the thickness after 30 minutes' recovery.

• Method B: CB = (t0 − ti) ÷ (t0 − tn) × 100, where tn is the spacer bar thickness.

• Applied deflection (Method B check): (t0 − tn) ÷ t0 × 100.

Worked example (Method B, Type 1, 22 h at 100 °C): a disc measures t0 = 12.52 mm and is compressed on 9.50 mm spacers. The applied deflection is (12.52 − 9.50) ÷ 12.52 = 3.02 ÷ 12.52 = 24.1 %. After aging and 30 minutes' recovery it measures ti = 11.65 mm. CB = (12.52 − 11.65) ÷ (12.52 − 9.50) × 100 = 0.87 ÷ 3.02 × 100 = 28.8 %. Two more discs give 27.9 % and 29.6 %, so the median of three is 28.8 %.

Worked example (Method B, Type 2): t0 = 6.02 mm, tn = 4.50 mm, ti = 5.40 mm. CB = (6.02 − 5.40) ÷ (6.02 − 4.50) × 100 = 0.62 ÷ 1.52 × 100 = 40.8 %.

Worked example (Method A): t0 = 12.48 mm and ti = 12.06 mm after aging under 1.8 kN and recovery. CA = (12.48 − 12.06) ÷ 12.48 × 100 = 0.42 ÷ 12.48 × 100 = 3.4 %. This is not a better compound than the Method B example; it is a different basis. Method A divides by the whole thickness, Method B by the deflection.

Typical compression set values

• Values below are rough orientation for Method B at about 25 %; compound, cure and time move them a great deal.

• Good sealing compounds at their rated temperature: often 10 to 30 % after 22 h.

• General-purpose compounds or a demanding temperature: 30 to 50 %.

• Above 50 to 60 %: the compound has lost most of its sealing force at that condition.

• 70 h results are higher than 22 h at the same temperature, and results rise steeply with temperature. Peroxide-cured EPDM, bisphenol-cured FKM and well-cured silicone are known for low set; under-cured or sulfur-cured compounds at high temperature for high set.

Precision: how much scatter to expect

The D395 precision statement is based on a small interlaboratory program (in the 2003 edition, two rubbers in five laboratories), so treat the published repeatability and reproducibility as indicative. In practice, results within one lab usually agree to within a few percentage points, while differences between labs of 5 to 10 points are not unusual for the same compound. Most of the scatter comes from cure state, plied versus solid specimens, spacer accuracy, oven uniformity, the delay between opening the fixture and the start of recovery, and thickness-gauge technique. When a result sits near a specification limit, agree specimen type, time, temperature and recovery with the other lab in advance.

What to report

• The standard and edition, the method (A, B or C) and specimen type (Type 1 or 2), and whether specimens were molded, cut or plied.

• Compound and cure details, and conditioning.

• Test time and temperature, and for Method B the spacer height and applied deflection.

• Original and final thickness of each specimen, the individual results and the average or median.

• Recovery time and conditions, and any lubricant used on the plates.

Common ASTM D395 problems and how to fix them

• Wrong formula: using the Method A formula on Method B data, or the other way round. Method B divides by the deflection.

• Spacers not matched to the specimen: a Type 2 spacer with a Type 1 disc, or worn spacers. Check tn and the applied deflection on every test.

• Uneven bolt tightening: plates not seated on all spacers, so discs see different deflections. Tighten in a crossing pattern and check.

• Late opening or cooling in the fixture: the discs recover less and read high. Open promptly and recover on wood for exactly 30 minutes.

• Cupped or non-parallel discs: from flat die-cutting or a dull rotating die. Use a sharp rotating die with soap solution.

• Mixing plied and solid results: report them separately.

• Too soon after cure: wait at least 24 hours; under-cured specimens read high.

• Overloaded oven: fixtures shield each other and the temperature varies. Leave space for air circulation.

• Heavy-foot thickness gauge: a gauge that squeezes the disc reads low. Use a D3767 gauge and the same technique before and after.

• Testing hard compounds by Method B: above 90 IRHD, use the hardness-based method your specification calls for.

ASTM D395 vs. ISO 815-1 and related ASTM methods

• ISO 815-1: compression set at ambient or elevated temperature. Its large test piece is the same 29 mm diameter, 12.5 mm disc, its small one is 13 mm diameter by 6.3 mm, and the compression is 25 % for most compounds, reduced for harder materials. ISO 815-1 offers more than one way of releasing and recovering the specimen, so align the procedure, not just the specimen, before comparing data.

• ISO 815-2: compression set at low temperatures.

• ASTM D1229: compression set at low temperature (ASTM's counterpart to ISO 815-2).

• ASTM D1414: O-ring testing, which runs compression set by D395 Method B on cut sections at 25 %; see our D1414 O-ring guide.

• ASTM D1056: sponge and expanded rubber, which uses a modified Method B at 50 % deflection with its own times and recoveries.

• ASTM D3574: flexible polyurethane foam, which has its own constant-deflection compression set test at higher deflections.

• ASTM D575: compression-deflection of rubber, measuring stiffness rather than permanent set, on the same Type 1 disc.

Related rubber tests

• ASTM D412: tensile strength and elongation of rubber; see the D412 complete guide.

• ASTM D624: tear strength of rubber; see the D624 complete guide.

• ASTM D575: compression-deflection.

• ASTM D1414: O-ring tests, including tensile and compression set.

• See our elastomers, foam and compression testing pages for the full range.

Complete ASTM D395 equipment packages

Basic compression set and QC station

• ASTM D395 Method B compression set fixture with Type 1 or Type 2 spacers

• An air-circulating aging oven and a D3767 dial thickness gauge

• A rotating hollow cutting die for discs

• Optional: a Mark-10 F755 with compression platens for D575 and roller grips for D412 and D624

Advanced rubber development and certification lab

• Method B fixtures for both specimen types, plus a Method A device if your specifications call for it

• Galdabini 5 kN or 10 kN universal testing machine with compression platens

• Pneumatic grips and D412 and D624 cutting dies on an arbor press

• UGC-VE-2109 video extensometer for D412 elongation

• Environmental chamber for frame-based tests from −80 to +280 °C, plus an aging oven for D395

ASTM D395 FAQ

What is ASTM D395?

The ASTM standard for compression set of rubber. A disc is compressed by a fixed force (Method A) or a fixed deflection (Methods B and C), held at temperature for a set time, released, and the permanent loss of thickness is reported as a percentage.

What is the difference between Method A and Method B?

Method A applies a constant 1.8 kN force and calculates set on the original thickness. Method B compresses the disc about 25 % with spacer bars and calculates set on the deflection applied. Method B is the default.

What is ASTM D395 Method C?

A constant-deflection method in which the compression depends on the material's hardness, similar to ISO 815-1. It provides a route for compounds where 25 % compression is unsuitable, including those above 90 IRHD. Check the current edition for its details.

What are the ASTM D395 specimen sizes?

Type 1 is 29.0 ± 0.5 mm in diameter and 12.5 ± 0.5 mm thick, for Methods A and B. Type 2 is 13.0 ± 0.2 mm in diameter and 6.0 ± 0.2 mm thick, for Method B.

What spacer height is used for Method B?

About 9.5 mm for Type 1 discs and 4.5 mm for Type 2, which gives roughly 25 % compression. Always check the actual deflection from the measured disc thickness.

How is compression set calculated?

Method B: CB = (t0 − ti) ÷ (t0 − tn) × 100. For example, t0 = 12.52 mm, ti = 11.65 mm and tn = 9.50 mm give 28.8 %. Method A: CA = (t0 − ti) ÷ t0 × 100.

What time and temperature does ASTM D395 use?

22 hours or 70 hours are the standard periods. The temperature comes from the material specification, typically 70 °C to 200 °C depending on the polymer.

How long is the recovery time?

30 minutes at standard laboratory temperature, with the specimens on a poor heat conductor such as wood, before measuring the final thickness.

Can I use plied specimens?

Yes. Up to 7 plies for Type 1 and 4 for Type 2, stacked without cement. Plied results can differ from solid discs, so compare like with like.

Do I need a testing machine for ASTM D395?

Not for Method B, which uses a spacer fixture, an oven and a thickness gauge. A frame is useful for Method A load verification and for related tests such as D575, D412 and D624.

Do I need an extensometer for ASTM D395?

No. Compression set comes from two thickness readings. Extensometers belong to D412 elongation testing in the same lab.

What is a good compression set value?

Lower is better. Good sealing compounds often reach 10 to 30 % at their rated temperature after 22 hours; values above 50 % mean most of the sealing force has been lost.

Is ASTM D395 the same as ISO 815-1?

They are close but not identical. Specimens and the 25 % compression are similar, but ISO 815-1 differs in small-specimen height and recovery options, so align the procedure before comparing results.

Related reading

• ASTM D395 compression set fixture page

• ASTM D412 complete guide: rubber tensile testing

• ASTM D624 tear strength complete guide

• O-ring tensile testing equipment for ASTM D1414

• Temperature chamber buyer's guide

• Mark-10 test frame vs. universal testing machine

• What is a universal testing machine?

Get a complete ASTM D395 system

Universal Grip supplies the ASTM D395 Method B compression set fixture and everything around it in a rubber lab: compression platens and compression fixtures for D575, pneumatic and roller grips and cutting dies for D412 and D624, environmental chambers, video extensometers, and testing machines from a Mark-10 tensile tester to a Galdabini universal testing machine. Contact us with your specimen type, method, temperatures and the other rubber tests you run, and we will configure a system and quote it.