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Home >> Application >> By Standard >> ASTM >> ASTM D >> ASTM D4804 Thin Film Vertical Burning Test

ASTM D4804 Thin Film Vertical Burning Test

ASTM D4804 Flexible Plastic Flammability Tester | UnitedTest

UnitedTest manufactures ASTM D4804 compliant testing machines for nonrigid solid plastics vertical burning test. ASTM D4804 is a small-scale vertical burning lab test for thin flexible plastics that distort under ASTM D3801, supporting VTM‑0, VTM‑1, VTM‑2 flammability classification.

ASTM D4804 is a small‑scale vertical‑burning laboratory test designed for thin, flexible non‑rigid solid plastics that deform, shrink or burn up to clamps when tested by ASTM D3801 (rigid plastic vertical burning). It provides optional VTM‑0/VTM‑1/VTM‑2 classification for flexible thin plastics, and is not intended for building construction or finishing plastics. UnitedTest supplies professional ASTM D4804 flammability testing equipment for material R&D, laboratory certification and quality inspection of thin flexible polymer materials.

Test principle

A strip of thin, flexible plastic is rolled into a lapped cylinder and hung vertically from a clamp. A calibrated 20 ± 1 mm methane test flame is applied to the bottom (unlapped) end for 3 ± 0.5 s, withdrawn, and the afterflame time is recorded. The flame is immediately re-applied for a second 3 ± 0.5 s, then withdrawn again, and both afterflame and afterglow times are recorded. A layer of dry surgical cotton 300 mm below the specimen detects whether flaming drips/particles fall and ignite it.

The underlying logic: a material that stops flaming quickly, does not glow on, does not burn up to the 125 mm mark, and does not drip flaming debris is a better fire performer. Two flame applications simulate re-ignition of an already-charred/heated material.

Thin, nonrigid plastics distort, shrink, curl away from the flame, or are consumed up to the holding clamp when tested with ASTM D3801 (the standard vertical test for rigid plastics, source of V-0/V-1/V-2). D4804 solves this by supporting the film on itself — rolling it into a self-supporting tube — so the burning behaviour of genuinely thin, floppy materials can be measured reproducibly.

Test Specimen Information

Standard dimension: 200 ±5 mm long × 50 ±2 mm wide, maximum thickness 0.25 mm. Thicker specimens may be tested only if they deform excessively in D3801 test.
Preparation: Mark 125 ±5 mm line from the bottom edge. Wrap tightly around the 13 mm mandrel to form a lapped cylinder. Secure overlapping upper section with adhesive tape or nichrome wire, remove mandrel afterwards.
Sample quantity: Minimum 20 specimens total (two conditioning groups, 5 specimens per group, plus spares for retest).

Test equipment required for ASTM D4804 Thin Film Vertical Burning Test

Recommend UntiedTest UL94 Horizontal & Vertical Flame Tester, consist of below:

Test chamber / hood	≥ 0.5 m³, no induced or forced draft; dark interior; light level < 20 lx at specimen position; exhaust fan to remove combustion products (products are toxic); rear-view mirror recommended
Laboratory burner	Complies with ASTM D5025, calibrated per ASTM D5207 monthly or upon equipment/gas change
Ring stand + clamp	Adjustable spring clamp, grips the upper 6 mm, closes the tube top to prevent chimney effect
Timing device	Accuracy ±0.5 second;
Gas supply	Technical-grade methane, ≥ 98 % pure (referee gas in disputes); natural gas of 37 ± 1 MJ/m³ (1000 Btu/ft³) gives similar results; butane, propane, acetylene are NOT suitable (energy density too high).

Key Test Parameters

Test flame height	20 ± 1 mm blue flame (yellow tip just removed by air adjustment); calibrated per Practice D5207 monthly, and whenever gas/equipment changes or results are questioned
Flame application time	3 ± 0.5 s, applied twice
Burner-to-specimen distance	Burner tube top 10 ± 1 mm below specimen bottom; flame withdrawn ≥ 150 mm between applications
Specimen-to-cotton distance	300 ± 10 mm
Testing window	Within 30 min of removal from conditioning
Cotton conditioning	≥ 24 h in desiccator; use within 30 min of removal
Measured outputs	afterflame time t₁ (1st application), afterflame t₂ and afterglow t₃ (2nd application), dripping/ignition of cotton, burn up to the 125 mm mark

Test procedure of ASTM D4804 Thin Film Vertical Burning Test

Set up — work in a draft-free chamber; clamp the specimen by its upper 6 mm with the axis vertical, top closed (no chimney effect), bottom 10 ± 1 mm above the burner tube and 300 ± 10 mm above the cotton layer.
Flame preparation — ignite the burner away from the specimen, adjust gas and air ports to a 20 ± 1 mm yellow-tipped blue flame, then increase air until the yellow tip just disappears; re-check height.
First application — place the flame centrally under the lower end of the unlapped section for 3 ± 0.5 s; withdraw ≥ 150 mm; record afterflame time t₁. (For flared, non-lapped specimens, apply the flame in line with the longitudinal axis)
Second application — as soon as flaming ceases, re-apply for 3 ± 0.5 s; withdraw; record afterflame t₂ and afterglow t₃.
Dripping handling — if the specimen drips molten/flaming material, tilt the burner up to 45° and offset it to avoid drips entering the burner tube; if the specimen is consumed, hand-hold the burner maintaining the correct distance; ignore molten strings and always flame the bottom of the major portion.
Repeat for all specimens in each set.

Industry Application Fields

Electrical & electronic equipment — insulation films, flexible printed-circuit substrates, cable wrap/tape, connector and transformer insulation, appliance internal flexible parts (this is the domain where its twin IEC 60695-11-10 / UL 94 Section 11 is applied for product safety certification and UL "Yellow Card" listings).
Wire & cable — thin jacketing, sleeving, shrink tubing, wrapping films.
Automotive, aerospace, rail — interior trim films, flexible ducting, wire-harness wrap, seating/laminate films.
Packaging & consumer goods — decorative and functional films, labels, flexible laminates, synthetic leather.
Plastics industry R&D and QA — quality assurance and pre-selection of component materials, batch-to-batch consistency, formulation screening (flame retardants, pigments, fillers), and thickness/colour/additive effect studies
Explicitly excluded: plastics used as building construction or finishing materials, and it is not a fire-risk/fire-hazard assessment on its own.

Related Test Standard:

IEC 60695‑11‑10	50 W horizontal & vertical flame test methods
UL 94	Widely‑used North‑American standard for plastic flammability (HB horizontal burn; V‑0/V‑1/V‑2 vertical burn). Its test setup and evaluation criteria are highly analogous to ISO 1210 / IEC 60695‑11‑10.
ASTM D635	US horizontal‑burning rate test for plastics (similar to ISO 1210 Method A).
ISO 1210	Plastics; determination of the burning behaviour of horizontal and vertical specimens in contact with a small-flame ignition source
IEC 60695‑11‑20	500 W flame (5V classifications), the "bigger flame" counterpart.
ISO 9773	vertical burning of thin flexible films/sheets (for materials that shrink away, which ISO 1210 cannot handle).
ISO 9772	cellular plastics, horizontal small‑flame burning.
ASTM D3801	vertical, 20 mm flame
ASTM D4804	thin flexible
GB/T 2408 (China), AS/NZS 60695.11.10, JIS C 60695‑11‑10, UNE‑EN 60695‑11‑10 — national adoptions of IEC 60695‑11‑10.

Keywords: ASTM D4804,nonrigid solid plastics flammability test,flexible plastic vertical burning tester,VTM-0 VTM-1 VTM-2 test,thin flexible plastic flame test,ASTM D3801 alternative test,plastic flammability characteristics tester,polymer flammability lab equipment,UnitedTest flammability tester,vertical burn test machine for thin plastic,flexible plastic fire response test,plastic material fire rating test,non-rigid plastic combustion tester,flammability classification test equipment,thin polymer sheet burning test

Related products and device

ASTM D4804 Thin Film UL94 Horizontal & Vertical Flame Tester

UL94 horizontal vertical flame tester, standard UL94 flammability test chamber for plastic, rubber, foam, electronic material fire resistance test, supports HB/V0/V1/V2/5VA/5VB/VTM/HBF test grades, PLC touch screen automatic timing, 50W & 500W dual burner, 1-year full warranty, factory direct export

ISO 4589-2 Plastics burning Oxygen Index Test Apparatus / LOI tester

Oxygen Index Apparatus/LOI tester (Limitation Oxygen Index tester) is widely used to measure burning performance of plastics, rubber, fiber, foam,,film etc., The technique measures the minimum percentage of oxygen in the test atmosphere that is required to marginally support combustion.

Related Standard

ISO 4589-3 High Temperature Oxygen Index Test Temperature Index (TI) and Flammability Temperature (FT) –

ISO 4589-3 — Plastics — Determination of burning behaviour by oxygen index — Part 3: Elevated-temperature test.

ISO 4589-3 defines two core output parameters: Temperature Index (TI) — the minimum oxygen volume fraction sustaining flaming combustion at an elevated test temperature; and Flammability Temperature (FT, Annex A normative method) — the temperature at which a specimen just burns in normal air (20.9 % oxygen).

it takes the classic oxygen-index (OI) test and runs it hot, to answer "how flammable is this plastic when it is already hot?"

ASTM D2863 Oxygen Index Test — LOI Testing for Plastics, Rubber, Foam & Film –

ASTM D2863 Standard Test Method for Measuring the Minimum Oxygen Concentration to Support Candle-Like Combustion of Plastics (Oxygen Index)

ASTM D2863 measures the Oxygen Index (OI), also called the Limiting Oxygen Index (LOI):

Oxygen Index (OI) — the minimum concentration of oxygen, expressed as volume percent, in a mixture of oxygen and nitrogen that will just support flaming combustion of a material initially at 23 ± 2 °C under the conditions of this test method.

In plain terms: it answers the question "How much oxygen does this plastic need in the air around it to keep burning like a candle?"

Key interpretive benchmark: Ambient air contains ~21 % oxygen. Therefore:

OI ≤ 21 % → the material will continue to burn in normal air

OI > 21 % → the material is self-extinguishing in normal air (higher = more flame retardant)

ISO 9773 Thin Flexible Plastic Vertical Burning Test –

ISO 9773 Plastics — Determination of burning behaviour of thin flexible vertical specimens in contact with a small flame ignition source

ISO 9773 specifies a small‑scale laboratory screening method to evaluate relative burning performance of thin, flexible vertically‑oriented plastic specimens exposed to a low‑energy small‑flame ignition source. These thin flexible samples distort or shrink away from flame in IEC 60695‑11‑10 Method B and cannot be evaluated by that vertical‑burn procedureISO. The test measures afterflame time and afterglow time.

ISO 1210 Plastics Horizontal-Vertical Flammability Burning Test –

ISO 1210 Plastics: determination of the burning behaviour of horizontal and vertical specimens in contact with a small-flame ignition source

ISO 1210 evaluating the relative burning behaviour of plastic bar specimens exposed to a small‑flame ignition source. It defines two independent test methods: Method A (horizontal burning test) and Method B (vertical burning test). It measures after‑flame time, after‑glow time, damaged length and linear burning rate for comparison of plastic flammability performance.

IEC 60695-11-10 50W Horizontal & Vertical Flame Test –

IEC 60695-11-10 Fire hazard testing - Part 11-10: Test flames; 50 W horizontal and vertical flame test methods

IEC 60695-11-10 define small‑scale laboratory procedures to compare the burning behaviour of materials used in electrotechnical products, using bar specimens exposed to a 50 W nominal small flame ignition source. It determines either the linear burning rate (Method A) or the self‑extinguishing properties (Method B). Applicable to solid and cellular materials with apparent density > 250 kg/m³ (ISO 845).

ASTM D635 Plastic Horizontal Burning Test –

ASTM D635 Standard Test Method for Rate of Burning and/or Extent and Time of Burning of Plastics in a Horizontal Position

ASTM D635 is a small‑scale laboratory screening procedure for comparing the relative linear rate of burning, or the extent and time of burning (or both), of plastics in bar form — molded or cut from sheets, plates, or panels — tested horizontally. It is a fire‑test‑response method: it measures and describes response to heat and flame under controlled conditions, and it explicitly does not by itself constitute a fire hazard or fire risk assessment.

ASTM D4804 Thin Film Vertical Burning Test - Frequently Asked Questions (FAQs)

Q1. What is ASTM D4804?

ASTM D4804-25 is the Standard Test Method for Determining the Flammability Characteristics of Nonrigid Solid Plastics. It is a small-scale laboratory fire-test-response method in which a thin, flexible plastic specimen is rolled into a self-supporting cylinder, held vertically, and exposed twice to a 20 mm (50 W) methane test flame for 3 seconds. Afterflame and afterglow times, dripping behaviour, and whether the specimen burns up to a 125 mm mark are recorded. Results are used for the VTM-0 / VTM-1 / VTM-2 classifications.

Q2. Why does this test exist at all? Why not just use the normal vertical burning test?

Because thin, floppy films misbehave. Under ASTM D3801 (the vertical test for rigid plastics), a thin film shrinks, curls away from the flame, melts, or is consumed right up to the holding clamp — so no valid, repeatable measurement is possible. D4804 solves this by wrapping the specimen around a 13 mm mandrel into a lapped cylinder so the material supports itself during burning.

Q3. What does "nonrigid solid plastic" mean here?

It refers to films, sheets and thin laminates that cannot support themselves in the test position — typically ≤ 0.25 mm thick — e.g. flexible printed-circuit substrates, insulation films, cable wrap, tapes, labels, decorative and packaging films, and synthetic leather.

Q4. Is D4804 the same as UL 94?

It is the ASTM twin of a UL 94 method. The standard states it is equivalent to ISO 9773, IEC 60695-11-10 and UL 94 Section 11 — the section that produces VTM ratings. Note carefully: VTM-0 is NOT equivalent to V-0 (different specimen form, different flame application time).

Q5. What flame application time is used — 3 s or 10 s?

3 s ± 0.5 s, applied twice. This differs from UL 94 V / ASTM D3801 (10 s twice) and from HB / D635 (30 s once), which is exactly why VTM and V ratings cannot be compared directly.

Q6. What are the specimen dimensions and how is it prepared?

200 ± 5 mm long × 50 ± 2 mm wide × maximum 0.25 mm thick. A line is marked 125 ± 5 mm from the bottom; the strip is wrapped tightly around a 13 ± 0.5 mm mandrel to form a lapped cylinder, with the overlap secured by pressure-sensitive tape within the upper 75 mm (or nichrome wire for stiff specimens). The mandrel is then removed. A minimum of 20 specimens is prepared.

Q7. Can thicker materials (> 0.25 mm) be tested by D4804?

Yes — but only if, because of thinness and nonrigidity, they distort, shrink, or burn up to the clamp when tested by D3801. Thickness must always be measured (to 0.01 mm) and reported, because results are only comparable at the same thickness.

Q8. Why must methane be used, and why must the flame be calibrated?

Methane (≥ 98 %) is the referee gas because flame energy density directly drives ignition severity; propane/butane/acetylene are hotter and would make results non-comparable. D5207 calibration (with a thermocouple/copper-block verification of the 20 mm flame) is what makes data from different labs and different days comparable.

Q9. What is the cotton for, and how is it prepared?

It is the secondary-ignition indicator. If the specimen drips flaming particles that ignite the cotton 300 mm below, the material has demonstrated a real flame-spread hazard. Cotton is conditioned ≥ 24 h in a desiccator and must be used within 30 min of removal.

Q10. What are the VTM criteria?

Criteria	VTM-0	VTM-1	VTM-2
Afterflame, each specimen (t₁ or t₂)	≤ 10 s	≤ 30 s	≤ 30 s
Total afterflame, 5 specimens	≤ 50 s	≤ 250 s	≤ 250 s
Afterflame + afterglow after 2nd flame (t₂+t₃)	≤ 30 s	≤ 60 s	≤ 60 s
Burn/afterglow up to the 125 mm mark	No	No	No
Cotton ignited by flaming drips	No	No	Yes (allowed)

Q11. Which industries require it?

Electrical & electronics (flexible printed-circuit substrates, insulation films, cable wrap, appliance internals), wire & cable (sleeving, shrink tubing), automotive/aerospace/rail interior films and harness wrap, packaging and consumer goods films, and polymer R&D/QA for flame-retardant formulation screening and lot release.

Q12. Why is it important for the material supplier?

Because VTM-0/1/2 is the language used by UL, IEC and OEM specifications. Without a valid rating, a film cannot be specified into regulated products. The test is also cheap and fast (small specimen, ~20 strips, minutes each), making it practical for incoming-goods QA where cone calorimetry or full-scale fire testing would be prohibitive.

Q13. What are the most common causes of failed or non-repeatable tests?

Poorly rolled cylinders / "U"-shaped flared ends; uncalibrated flame or wrong gas; drafts in the chamber; specimen tested more than 30 min after conditioning; wet or over-thick cotton; and comparing results across different thicknesses, colours or additive loadings.

Q14. Why choose ASTM D4804 Non‑Rigid Plastics Flammability Test Machine from UnitedTest?

UnitedTest manufactures ASTM D4804‑25 flammability test chamber for non‑rigid solid plastics thin films. Perform VTM‑0 VTM‑1 VTM‑2 vertical burning test compliant with UL94 section11, ISO9773, IEC60695‑11‑10 for flexible sheet & polymer film flammability evaluation.

UnitedTest is professional manufacturer of ASTM D4804 flammability testing equipment, designed for vertical burning assessment of thin flexible non‑rigid solid plastics, polymer films and thin sheets. Our test chamber fully complies with latest ASTM D4804‑25 standard, equivalent to UL 94 Section 11, ISO 9773 and IEC 60695‑11‑10 requirements for VTM‑0, VTM‑1, VTM‑2 classification testing.

This vertical flammability tester solves the common lab challenge: thin flexible plastic specimens distort, shrink or burn to fixture clamps when tested by standard ASTM D3801 rigid‑plastic vertical burn method. UnitedTest’s ASTM D4804 test system includes complete accessories: 13 mm specimen mandrel, D5025‑compliant laboratory burner, precision timing device, surgical cotton holder, spring clamps plus nichrome wire assemblies for cylindrical‑shaped specimen mounting.

Our D4804 flammability chamber features minimum 0.5 m³ enclosed hood, dark inner surfaces, background light control, exhaust ventilation for toxic combustion smoke, accurate flame‑height adjustment for 20 ±1 mm test flame. It supports full test workflows: specimen vertical mounting, dual‑cycle 3‑second flame application, afterflame / afterglow time recording, flaming‑drip ignition observation of surgical cotton pad placed 300 mm below sample.

Ideal quality‑control and R&D testing equipment for plastic film manufacturers, electrical‑component factories, third‑party testing laboratories, material compounding houses. Perform both original‑condition and high‑temperature‑aged specimen flammability evaluation according to D4804 conditioning requirements. UnitedTest provides factory calibration, installation guidance and after‑sales technical support for your ASTM D4804 flammability lab setup.

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