top of page

ASTM D5034 - Textile Tensile Grab Test

ASTM D5034 Textile Tensile Grab Test
ASTM D5034 sample
Vise grip for ASTM D5034 fabric grab test
Universal Grip ASTM D5034 tensile grip for universal testing machines

Downloads: Textile Testing Training Deck & Overview - Full Guide (PDF) · ASTM D5034 PDF (PDF) · ASTM D5034 Tensile Grip – Universal Grip Data Sheet (PDF)

Written by Chris Thomas, Universal Grip Company · Reviewed by Frank Bertini · Updated October 23, 2026

ASTM D5034 is the grab tensile test for textile fabrics. A 100 mm (4 in) wide specimen is gripped only across its centre 25 mm (1 in), with 75 mm (3 in) between the jaws, and pulled at 300 mm/min (12 in/min) until it breaks. Because the unclamped yarns on either side help carry the load, the result is an effective breaking strength rather than the strength of a defined width.

This guide explains what the jaw-face rule really requires, how to prepare grab and modified grab specimens, speed and load-cell choice, conditioning and wet testing, the jaw-break rules, calculations with a worked example, and how the grab test compares with the ASTM D5035 strip test and ISO 13934-2.

Note: Current edition: ASTM D5034-21 (Reapproved 2025). The 2021 revision may word some clauses differently from earlier editions, so confirm details such as modified-grab jaw sizes in your own licensed copy.

What the grab test measures and who uses it

The full title is "Standard Test Method for Breaking Strength and Elongation of Textile Fabrics (Grab Test)", maintained by ASTM subcommittee D13.60. Note the wording: D5034 reports breaking strength, while its companion D5035 reports breaking force. Both are expressed in newtons or pounds-force. The test also gives apparent elongation, the extension at the breaking force as a percentage of the 75 mm gauge length.

The defining feature of the grab test is that the jaws are much narrower than the specimen. Only the central band of yarns is clamped, but the yarns next to it are held in place by the crossing yarns and share some of the load. The standard describes this as the effective strength of the fabric in use, including the assistance of adjacent yarns. That is why grab results cannot be compared directly with strip results or with yarn strength.

The grab test is accepted for commercial acceptance testing of most woven and nonwoven fabrics, and the modified grab for most wovens. It is widely written into apparel, workwear, home-furnishing and industrial fabric specifications. Labs that run it usually also run tear tests such as tongue tear to ASTM D2261 and trapezoid tear to ASTM D5587; see our textile testing guide and the textiles page for the full set.

D5034 is not recommended for glass fabrics (see ASTM D579 and D580) or for knitted and other fabrics with more than 11 % stretch. Fabrics stronger than about 200 N per cm of width (about 114 lbf per inch) may need a modified technique, such as a pin wrap.

ASTM D5034 at a glance

  • Standard: ASTM D5034-21 (Reapproved 2025), Breaking Strength and Elongation of Textile Fabrics (Grab Test)

  • Procedures: grab (G) and modified grab (MG); machine letters E (CRE), L (CRL) or T (CRT), for example G-E

  • Specimen: 100 ± 1 mm (4 in) wide and at least 150 mm (6 in) long, or 95 mm plus twice the jaw-face length

  • Centring line: drawn 37 ± 1 mm (1.5 in) from one long edge

  • Front jaw face: 25 ± 1 mm (1 in) across the specimen and 25 to 50 mm (1 to 2 in) along the load

  • Back jaw face: at least as large as the front face

  • Gauge length (distance between clamps): 75 ± 1 mm (3 ± 0.05 in)

  • Speed: 300 ± 10 mm/min (12 ± 0.5 in/min) on CRE, or a CRT setting giving a 20 ± 3 s time-to-break

  • Specimens: 5 warp (machine direction) and 8 filling (cross direction) per laboratory sample, for each condition

  • Force range: breaks between 10 % and 90 % of full scale

  • Conditioning: the ASTM D1776 standard atmosphere for testing textiles; wet testing optional

  • Results: average breaking strength (N or lbf) and average apparent elongation (%)

Grab vs modified grab

In the standard grab test (G), the 100 mm specimen is clamped by narrow front faces in the middle of its width and left whole. It suits woven, nonwoven and felted fabrics.

In the modified grab test (MG), the specimen is cut and marked the same way. Then slits are cut in from both long edges, midway between the ends and at right angles to the tested yarns, severing every tested yarn except the central 25 ± 1 mm. The clamped ends stay at full width, but only the central band carries load through the break zone, so the unclamped yarns can no longer help.

The modified grab is used mainly for woven fabrics. The standard notes it is useful where raveled strips keep unravelling during the test, which is common with high-strength fabrics. For high-strength fabrics the modified grab specimen may be at least 400 mm (16 in) long so it can be wrapped around pins. Report which procedure you used; G and MG results are not interchangeable.

Preparing grab specimens

Cut each grab specimen 100 ± 1 mm (4 in) wide and at least 150 mm (6 in) long, with the long dimension parallel to the yarns being tested. Grab specimens are cut, never raveled; raveling belongs to the D5035 strip test.

Why the line is drawn 37 mm from the edge

Draw a line 37 ± 1 mm (1.5 in) from one long edge, running along a yarn for the full length. When you mount the specimen, line the edge of the front jaw face up with this line. The arithmetic shows why: 37 mm of fabric on one side, 25 mm under the front face, and 38 mm on the other side add up to 100 mm. The line centres the grip on the specimen without measuring at the machine.

Minimum length: L = 95 + 2W

A note in the standard sets the minimum length at L = 95 + 2W in millimetres, where W is the jaw-face length along the load. The 95 mm covers the 75 mm gauge plus at least 10 mm projecting beyond each clamp. In inches, L = 4 + 2W.

  • 25 mm (1 in) long faces: 95 + 50 = 145 mm, so the 150 mm (6 in) minimum governs

  • 50 mm (2 in) long faces: 95 + 100 = 195 mm, so cut specimens at least 195 mm (about 8 in) long

  • A 100 × 200 mm specimen is a common, convenient size, but 200 mm is not a requirement

Where to cut them

Space specimens along a diagonal of the laboratory sample so that no two specimens for the same direction share the same yarns. Keep at least one-tenth of the fabric width away from each selvage. For paired conditioned and wet results, cut double-length specimens and divide them, so each half contains the same yarns.

Cutting a modified grab specimen

  • Cut and mark the specimen as for a grab test.

  • At mid-length, cut a slit in from each long edge at right angles to the tested yarns.

  • Stop the slits so the uncut band in the middle is 25 ± 1 mm wide and lines up with the front jaw face.

  • Check that every tested yarn outside that band is fully severed; a single uncut yarn adds strength.

Jaw faces: what D5034 actually requires

This is the most misquoted part of the standard. D5034 calls for smooth, flat jaw faces of metal or another agreed surface, parallel and with matching centres. For the grab test:

  • Front face: 25 ± 1 mm (1.0 ± 0.02 in) measured across the specimen, perpendicular to the load

  • Front face: 25 to 50 mm (1 to 2 in) measured along the load

  • Back face: at least as large as the front face in both directions

  • Use the same face sizes for every specimen in a set, and record them in the report

You will often see "1 × 1 in front, 1 × 2 in back" quoted as the requirement. It is not. A 25 × 25 mm (1 × 1 in) front face with a 25 × 50 mm (1 × 2 in) back face is a common commercial set-up that meets the rule, but it is one valid choice among several. A larger back face makes it easier to line up the front face and helps reduce slippage, which is why many labs use it. These combinations all comply:

  • 25 × 25 mm front with 25 × 50 mm back (the common kit)

  • 25 × 25 mm front with 25 × 25 mm back

  • 25 × 50 mm front with a back face of 25 × 50 mm or larger

Orientation matters. The 25 mm dimension of the front face must run across the specimen. A 25 × 50 mm face fitted the wrong way round grips 50 mm of width, and the test is no longer a grab test.

Modified grab faces

The modified grab procedure uses larger faces. In the text we reviewed, the top face is typically 25 × 50 mm (1 × 2 in) or larger, with the long side parallel to the load, and the bottom face 50 × 50 mm (2 × 2 in) or larger. Confirm these sizes in the current edition before ordering faces.

Face surface and the clamp check

Smooth metal is the standard's default. If specimens slip, or more than 25 % break at the jaw, the standard allows padding the jaws, coating the fabric under the clamp or changing the face, provided you report it. In our experience, rubber-coated faces are the usual fix for slick synthetics and coated fabrics. To check that faces clamp evenly, close them on a sandwich of white tissue, two carbon papers back to back, and white paper; the imprint should be complete and even.

Pins for high-strength fabrics

For fabrics above about 200 N/cm, the standard describes two stainless-steel pins 10 mm (3/8 in) in diameter and 125 mm (5 in) long. The specimen wraps around the pins between the jaws so friction takes up much of the load before it reaches the clamp. Over-tight clamps cause front-jaw breaks; loose clamps let the fabric slip. Contact us to discuss a pin-wrap fixture.

Pneumatic grips with interchangeable faces are the usual choice for grab testing, because the clamping force is the same for every specimen. Manual vise grips with quick-change inserts suit lower volumes.

Testing machine, speed and load cell

The tester must conform to ASTM D76 and may be CRE, CRL or CRT. CRE is preferred, and most modern electromechanical universal testing machines are CRE. Do not compare results from different machine types. In a dispute, the referee condition is a constant time-to-break of 20 ± 3 s; cut two or three extra specimens to set that rate.

Speed and gauge

Set the clamp separation to 75 ± 1 mm (3.0 ± 0.05 in) and the speed to 300 ± 10 mm/min (12 ± 0.5 in/min). That is a nominal strain rate of 400 % per minute, so a fabric that breaks at 28 % elongation reaches 21 mm of extension in about 4 seconds. Grab tests on a CRE frame are short. Our advice, not a requirement of the standard: acquire data at 50 to 100 points per second or faster so the peak is captured.

Load cell sizing

Choose a range so every break falls between 10 % and 90 % of full scale. Most apparel wovens typically grab-break between about 200 N and 1.2 kN (45 to 270 lbf). Heavy industrial, flame-resistant and coated fabrics can reach 2 to 5 kN, so a 5 kN load range covers nearly all grab work. A 10 kN machine is not required; what matters is that breaks sit inside the 10 to 90 % band. A benchtop frame suits most textile labs, and very light fabrics can go on a smaller tensile tester.

System check

Check the system with standard fabrics at least weekly and after any change to the load cell or clamps. Mark the specimen at the jaw edges to spot slippage; if it slips, raise the air pressure or tighten the clamps, and use cushions if that causes jaw breaks.

Sampling, conditioning and wet testing

Take the lot sample from rolls or pieces: all of them for 1 to 3, four for 4 to 24, five for 25 to 50, and 10 % (maximum 10) above 50. From each, cut a laboratory sample the full fabric width and 1 m (1 yd) long. From each laboratory sample, test 5 warp and 8 filling specimens for each condition. Filling results scatter more, so filling needs more specimens. "3 + 3" and "5 + 5" plans do not meet the standard.

Conditioning

Precondition if the fabric is wetter than equilibrium, then condition in the ASTM D1776 standard atmosphere for testing textiles, nominally 21 °C (70 °F) and 65 % relative humidity. Recent editions of D1776 changed the tolerances, so use the values in your current copy. Equilibrium is reached when mass changes by no more than 0.1 % between weighings at least 2 h apart. Routine minimum times are 8 h for wool and viscose, 6 h for cotton, 4 h for acetate and 2 h for low-regain fibres.

Wet testing

  • Soak specimens in room-temperature water, routinely for 1 h, with up to 0.05 % nonionic wetting agent if needed.

  • Test each specimen within 2 minutes of removing it from the water.

  • Use paired halves so wet and conditioned results come from the same yarns.

  • If unsized wet strength is needed, desize first as described in ASTM D629.

  • The standard also includes an optional allowance for wet shrinkage based on yarn counts. Check the formula in your current edition, and report whether an allowance was applied.

Step-by-step ASTM D5034 procedure

  • Fit front faces 25 ± 1 mm across and back faces at least as large; run the carbon-paper check on new faces.

  • Set the clamp separation to 75 ± 1 mm, the speed to 300 ± 10 mm/min (or the CRT rate), and a load range that puts breaks between 10 % and 90 %.

  • Condition the specimens, or soak them for wet testing.

  • Place the specimen in the upper jaw with the 37 mm line at the edge of the front face, roughly equal fabric extending beyond each jaw, and the long axis parallel to the load. Close the jaw.

  • If elongation is measured, hang the 170 g (6 oz) auxiliary clamp below the lower jaw to set the pretension. In the text we reviewed, pretension must not exceed 0.5 % of full-scale force.

  • Close the lower jaw with the 37 mm line again at the front-face edge and the tension even across the clamped width.

  • Mark the jaw edges on the specimen, zero the extension and run to rupture.

  • Record the maximum force, the extension at maximum force and the break location.

  • Keep warp and filling, and conditioned and wet, results separate. Apply the jaw-break rules and replace any discarded specimen.

Calculations and a worked example

Breaking strength is the average maximum force of the acceptable specimens for each direction and condition, in N or lbf. It is reported as a force, not as force per width or a stress, because the effective width carrying load in a grab test is unknown.

Apparent elongation (%) = (extension from the start of the force-extension curve to the breaking force ÷ 75 mm) × 100. It is apparent because the fabric creeps slightly out of the jaws, so the true deforming length is a little longer than 75 mm.

Worked example: G-E, warp direction

  • Maximum forces: 540, 515, 560, 530 and 555 N

  • Sum: 540 + 515 + 560 + 530 + 555 = 2,700 N

  • Average breaking strength: 2,700 ÷ 5 = 540 N (121.4 lbf)

  • Average extension at breaking force: 21 mm

  • Apparent elongation: 21 ÷ 75 × 100 = 28.0 %

  • Time to break: 21 mm at 300 mm/min (5 mm/s) is about 4.2 s

Keep or discard?

A sixth specimen broke 2 mm from the upper jaw at 250 N. Half the average of the other breaks is 540 ÷ 2 = 270 N. The break is within 5 mm of the jaw and below 270 N, so discard it and test a replacement. A specimen that broke 4 mm from the jaw at 500 N would be kept: it is near the jaw, but well above 50 % of the average.

Note: Report the code (here G-E), the number of specimens per direction, the force range, the pretension, the front and back jaw-face sizes, and any padding or face changes along with the averages.

Grab vs strip vs ISO 13934-2

D5034 and the D5035 strip test share the 75 mm gauge, 300 mm/min speed, 5 + 8 specimen plan, conditioning and jaw-break rules. They differ in how much of the fabric is gripped.

  • D5034 grab: 100 mm wide specimen, centre 25 mm gripped, unclamped yarns assist; result is an effective strength

  • D5034 modified grab: same specimen, slit to a 25 mm loaded band, so neighbouring yarns cannot assist

  • D5035 strip: 25 or 50 mm strip, raveled or cut, gripped across its full width; result is the force for that width

How much higher is grab than strip?

Grab results are higher than strip results, not lower. ASTM's 1991 interlaboratory study used the same three fabrics for the precision statements of both standards, tested on CRE machines at 65 % RH. The averages were approximately:

  • Filter fabric: grab 61.4 lbf vs strip about 52 lbf, a ratio of about 1.18

  • Plain weave: grab 112 lbf vs strip about 89 lbf, a ratio of about 1.26

  • Sateen: grab 240 lbf vs strip about 182 lbf, a ratio of about 1.32

In other words, grab results were about 1.2 to 1.3 times the strip results on the same fabrics. The extra force is yarn assistance from the unclamped yarns, and it changes with weave and construction. There is no reliable factor to convert one result to the other, so test to the method your specification names.

ISO 13934-2

ISO 13934-2 is the international grab method, but it is not equivalent to D5034. It typically runs much more slowly (about 50 mm/min) over a longer gauge (about 100 mm) and reports maximum force only, with ISO 139 conditioning. A speed six times lower and a different gauge give different numbers. Check the current ISO edition for its exact values.

Related methods

Jaw breaks and common errors

Jaw-break rules

  • Discard and retest specimens that slip, break at or in the jaws, or fall well below the average of the set.

  • A break within 5 mm (0.25 in) of a jaw is discarded only if it is below 50 % of the average of the other breaks.

  • If specimens slip, or more than 25 % break within 5 mm of a jaw edge, pad or coat or change the faces, and report the change.

Errors we see most often

  • Off-centre mounting. Ignoring the 37 mm line puts the front face near one edge and changes how many yarns assist.

  • Front face too wide or turned sideways. A face wider than 26 mm across the specimen is outside the rule.

  • Back face smaller than the front. The back face must be at least as large.

  • Too few filling specimens. The plan is 5 warp and 8 filling.

  • Mixing warp and filling, or wet and conditioned, in one average.

  • Comparing CRE with CRT data, or grab with strip data.

  • Slow wet tests. More than 2 minutes out of the water and the specimen starts drying.

  • Uncut yarns in a modified grab specimen, which raise the result.

Precision: what difference is significant?

The precision statement comes from the same 1991 study: three fabrics, three labs, two operators each. Single-operator coefficients of variation were roughly 2 to 5 %. For averages of five specimens, the critical differences at the 95 % level were roughly 3 to 7 % for a single operator and up to about 16 % between laboratories. No bias is known.

So a 5 % shift between two lots on one machine may be real, but a 10 % gap between your result and a supplier's may be within normal lab-to-lab spread. Check the precision section of your current edition for the exact table.

D5034 test equipment from Universal Grip

Universal Grip Company makes tensile grips and fixtures and distributes Galdabini universal testing machines. A grab-test set-up needs a CRE frame, a load cell sized for your fabrics, and grips with the right front and back faces.

Many labs run D5034, D5035 and ASTM D4632 on one frame by changing faces, and add ASTM D2261 tear tests on the same grips. Contact us with your fabrics, expected break force and the standards you need, and we will quote a complete grab-test system or grips for your current machine.

ASTM D5034 FAQ

What is the ASTM D5034 grab test?

ASTM D5034 is a tensile test for textile fabrics. A 100 mm (4 in) wide specimen is gripped only across its centre 25 mm by narrow jaws set 75 mm apart, then pulled at 300 mm/min until it breaks. It reports breaking strength in N or lbf and apparent elongation. The current edition is D5034-21, reapproved in 2025.

What is the difference between a grab test and a strip test?

The D5034 grab test clamps only the centre of a wide specimen, so unclamped neighbouring yarns help carry load. The D5035 strip test clamps a 25 or 50 mm strip across its full width. Grab results are higher: in ASTM's own study they were about 1.2 to 1.3 times the strip results on the same fabrics. The two cannot be converted.

What jaw-face size does ASTM D5034 require?

The front face must be 25 ± 1 mm (1 in) across the specimen and 25 to 50 mm (1 to 2 in) along the load. The back face must be at least as large as the front. A 25 × 25 mm front with a 25 × 50 mm back is a common set-up, but it is not the only compliant one.

What is the specimen size for D5034?

Grab specimens are 100 ± 1 mm (4 in) wide and at least 150 mm (6 in) long, or 95 mm plus twice the jaw-face length if longer. With 50 mm long faces that means at least 195 mm. A line is drawn 37 mm from one long edge to centre the front jaw face on the specimen.

What speed and gauge length does D5034 use?

The clamps are set 75 ± 1 mm (3 in) apart and the crosshead moves at 300 ± 10 mm/min (12 ± 0.5 in/min) on a constant-rate-of-extension machine. The alternative is a constant time-to-break machine set for a 20 ± 3 second break, which is also the referee condition when results are disputed.

What is the modified grab test?

The modified grab uses the same 100 mm specimen, but slits are cut in from both edges at mid-length so that only the central 25 mm of the tested yarns carries load. Neighbouring yarns can no longer help. It is used mainly for woven fabrics, especially high-strength fabrics where raveled strips keep unravelling during the test.

How many specimens does D5034 require?

For each laboratory sample and each condition, conditioned or wet, test 5 specimens in the warp (machine) direction and 8 in the filling (cross) direction. The extra filling specimens allow for the greater scatter in filling results. Plans of three or five per direction do not meet the method.

Why is a line drawn 37 mm from the edge of the specimen?

The line positions the 25 mm front jaw face in the middle of the 100 mm specimen. With the jaw edge on the line there is 37 mm of fabric on one side, 25 mm under the face and 38 mm on the other side. It lets the operator centre every specimen the same way without measuring at the machine.

How is apparent elongation calculated in D5034?

Apparent elongation is the extension from the start of the force-extension curve to the breaking force, divided by the 75 mm gauge length and multiplied by 100. For example, 21 mm of extension gives 21 ÷ 75 × 100 = 28.0 %. It is called apparent because the fabric slips slightly out of the jaws, lengthening the true gauge.

What if the fabric breaks at the jaw?

A break within 5 mm of a jaw is discarded if its value is below 50 % of the average of the other breaks; otherwise it counts. If specimens slip, or more than 25 % break within 5 mm of a jaw edge, pad the jaws, coat the fabric under the clamp or change the faces, and report the change.

Is ASTM D5034 the same as ISO 13934-2?

No. Both are grab tests, but ISO 13934-2 typically runs at about 50 mm/min over a gauge of about 100 mm and reports maximum force only, while D5034 runs at 300 mm/min over 75 mm and also reports elongation. The six-fold speed difference alone changes results. Check the current ISO edition for its exact values.

Can D5034 be used for knitted, stretch or glass fabrics?

D5034 is not recommended for knitted fabrics or any fabric with more than 11 % stretch, because the specimen narrows and extends too much for a meaningful grab result. It is also not recommended for glass fabrics, which are covered by ASTM D579 and D580. Elastic fabrics have their own methods, such as ASTM D4964.

bottom of page