Q.01

How is clothing flammability tested in the US?

In the US, clothing textiles are tested under the CPSC's Standard for the Flammability of Clothing Textiles, 16 CFR Part 1610. Specimens are held at 45° and touched with a standard flame for 1 second, and the time the flame takes to travel 127 mm (5 in) up the fabric is recorded [1]. Fabrics are tested before and after dry cleaning and laundering, and each one is put into one of three classes; Class 3 textiles "shall not be used for clothing" [2]. Children's sleepwear has its own, stricter vertical test under Parts 1615 and 1616.

Approach: I read the current eCFR text of 16 CFR Parts 1610, 1611, 1615 and 1616, the flammability standards issued under the Flammable Fabrics Act.

Scope of Part 1610

  • What it covers: fabric in a form ready for use in wearing apparel, including garments and costumes finished for consumer use [3].
  • What it does not apply to [4]:
    • hats that do not cover the neck, face or shoulders [5]
    • gloves not more than 14 inches long that are not attached to another garment [6]
    • footwear that has no hosiery in it and is not attached to another garment [7]
    • interlining fabrics [8]
  • Fabrics exempt from testing to support guaranties:
    • plain surface fabrics of any fiber weighing 2.6 oz/yd² or more [9]
    • fabrics of any weight made entirely from acrylic, modacrylic, nylon, olefin, polyester or wool, alone or in combination [10]
  • Too small to test: narrow fabrics and loose fibrous materials under 50 mm (2 in) wide are not tested, and neither are items from which a 50 × 150 mm specimen cannot be cut, such as leis, fringe and wigs [11].

The 45° test method

  1. Pick the fabric type and the worst-case direction or area. Preliminary trials find the fastest-burning direction for plain fabrics [12] or the quickest-burning area for raised-surface fabrics [13]. Specimens are 50 × 150 mm (2 × 6 in).
  2. Brush raised-surface fabrics. Each one is brushed once, against the lay of the fibers [14].
  3. Condition the specimens. They are dried in the oven for 30 ±2 min at 105 ±3 °C, then cooled over silica gel in a desiccator for at least 15 min [15].
  4. Ignite. A butane flame set to 16 mm (0.625 in) is applied for 1 second [16]. The test must begin within 45 seconds of taking the specimen out of the desiccator. Timing stops automatically when the flame burns through the stop thread [17].
  5. Record the results. The lab records the burn time and a visual result code for each specimen. Raised-surface specimens are left to keep burning so the lab can see whether the base fabric fuses [18].

Refurbishing (Step 2)

  • Dry cleaning first. All samples are dry cleaned before laundering, using either perchloroethylene or hydrocarbon solvent [19].
  • Then one wash and dry under AATCC LP1-2021 (Normal/Hot wash, Permanent Press tumble dry) [20].
  • No Step 2 for Class 3 fabrics. Samples already rated Class 3 in their original state are not refurbished [21].

Classification

ClassPlain surfaceRaised surface
1, NormalBurn time 3.5 s or more [22]More than 7.0 s, or a surface flash (0.0-7.0 s) that does not ignite or fuse the base fabric [23]
2, Intermediate ("may be used for clothing")Not applicable [24]4.0-7.0 s inclusive, with base burns (SFBB) [25]
3, Rapid and intense (banned for clothing)Less than 3.5 s [26]Less than 4.0 s, with base burns (SFBB) [27]

How many specimens are tested:

  • Plain fabrics: five specimens are tested first. Five more are added if the average burn time is under 3.5 s. Class 3 is assigned only when the 10 specimens give two or more burn times averaging under 3.5 s [28].
  • Raised fabrics: Class 3 requires an average under 4.0 s across 10 specimens with three or more base burns [29].
  • Inconclusive results: if only one of the 10 specimens gives a burn time, the fabric cannot be classified [30].
  • Final class: whichever is more severe, before or after refurbishing [31].

Related standards

  • Vinyl plastic film in apparel (Part 1611): covers nonrigid, unsupported vinyl film [32]. Coated fabrics other than nitro-cellulose-coated ones may be tested under the Part 1611 procedures [33].
  • Children's sleepwear, sizes 0-6X (Part 1615) [34] and sizes 7-14 (Part 1616) [35]:
    • Specimens of 8.9 × 25.4 cm are hung vertically, and a flame is applied along the bottom edge [36].
    • The average char length of five specimens shall not exceed 17.8 cm (7.0 in) [37].
    • No single specimen may char its full 25.4 cm (10 in) length [38].
    • Manufacturers and importers must group items into production units and test samples from each unit [39].
Q.02

How do the fabric burn-time classifications work?

Under 16 CFR Part 1610, a fabric's class depends on its average burn time. Burn time is the time from ignition until the stop thread is cut [40]. For raised-surface fabrics such as pile, nap or tufting, the class also depends on how many specimens show a "base burn" (SFBB) [41]. Plain fabrics can only be Class 1 or Class 3. Raised fabrics can also land in Class 2, and the cut-offs for raised fabrics are 4.0 and 7.0 seconds rather than 3.5 seconds.

Approach: I read the current eCFR text of 16 CFR Part 1610: the definitions (§ 1610.2), the classes (§ 1610.4), the test sequence (§ 1610.7) and the result codes (§ 1610.8).

The three classes (§ 1610.4)

ClassPlain surfaceRaised surface
1, Normal: acceptable for clothing [42]Burn time 3.5 s or more [22]Burn time over 7.0 s, or a surface flash (0.0-7.0 s) too weak to ignite or fuse the base fabric [23]
2, Intermediate: raised fabrics only; "may be used for clothing" [43]Not applicable [24]4.0 to 7.0 s (both inclusive), with base burns (SFBB) [25]
3, Rapid and intense: "shall not be used for clothing" [2]Less than 3.5 s [26]Less than 4.0 s, with base burns (SFBB) [27]

What counts as a base burn: the flame burns the base fabric and keeps burning on its own. It only counts toward Class 2 or 3 if it starts somewhere other than the point where the test flame touched (code SFBB). A lab can spot one by a change in opacity, scorching on the back of the fabric, or a hole [44].

How the results are applied (§ 1610.7)

Plain-surface fabrics

  • First five specimens: these are cut from the fastest-burning direction [45]. The fabric is Class 1 if any of these apply:
    • no specimen gives a burn time [46]
    • only one specimen gives a burn time, and it is 3.5 s or more [47]
    • two or more specimens give burn times that average 3.5 s or more [48]
  • When five more are tested: if the single burn time, or the average, is under 3.5 s [49].
  • Result across all 10:
    • Class 3 only when two or more burn times average under 3.5 s [28]
    • Class 1 if they average 3.5 s or more [50]
    • inconclusive, and the fabric cannot be classified, if only one of the 10 gives a burn time [30]

Raised-surface fabrics, first five specimens (cut from the most flammable area)

  • Class 1 if any of these apply:
    • no specimen gives a burn time [51]
    • there are no SFBBs, whatever the burn times [52]
    • the average is 0.0-7.0 s with surface flash only [53]
    • the average is over 7.0 s, with any number of SFBBs [54]
    • the average is 4.0-7.0 s with no more than one SFBB [55]
    • the average is under 4.0 s with no more than one SFBB [56]
  • Class 2 if the average is 4.0-7.0 s with two or more SFBBs [57].
  • Five more specimens are tested if there is a single burn time under 4.0 s with an SFBB, or an average under 4.0 s with two or more SFBBs [58].

Raised-surface fabrics, across all 10 specimens

  • Class 3 only if the average is under 4.0 s with three or more SFBBs [29].
  • Class 1 if any of these apply:
    • the average is under 4.0 s with no more than two SFBBs [59]
    • the average is 4.0-7.0 s with no more than two SFBBs [60]
    • the average is over 7.0 s [61]
  • Class 2 if the average is 4.0-7.0 s with three or more SFBBs [62].
  • Inconclusive if only one of the 10 gives a burn time [63].

After refurbishing (Step 2): the same rules are applied again to the dry-cleaned and laundered fabric [64][65]. The final class is whichever result is more severe, before or after refurbishing [31][66].

Result codes recorded for each specimen (§ 1610.8)

  • Plain fabrics:
    • DNI: did not ignite [67]
    • IBE: ignited, but extinguished [68]
    • the measured burn time [69]
  • Raised fabrics:
    • SFBB: base burn starting away from the point where the flame touched [70]
    • SFBB poi: base burn starting at that point [71]
    • SFBB poi*: base burn that possibly started at that point, where the origin cannot be determined [72]
    • SF only: surface flash with no damage to the base fabric [73]
    • SF poi: surface flash only where the flame touched, treated as "did not ignite" [74]
    • SF uc: surface flash under the stop thread that does not break it [75]
    • SF pw: surface flash part way, with no time because it did not reach the stop thread [76]
Q.03

What testing and certification do clothing manufacturers need?

Summary: A US clothing maker needs two kinds of testing. CPSC requires a certificate backed by flammability testing, and FTC rules require labelling backed by evidence.

  • Every garment: the manufacturer or importer, and the private labeler if there is one, "shall issue a certificate" saying the product meets every applicable CPSC rule, ban or standard. The certificate is based on "a test of each product or upon a reasonable testing program" [77]. For clothing, the key standard is 16 CFR Part 1610 (flammability), with Part 1615/1616 for children's sleepwear.
  • Children's clothing (designed or intended mainly for children 12 or under) [78]: the bar is higher. You need testing by a CPSC-accredited third-party lab, a Children's Product Certificate, ongoing periodic testing, and permanent tracking marks.

Approach: I read the Consumer Product Safety Act (15 U.S.C. ch. 47, 2023 edition), the current eCFR text of 16 CFR Parts 1610/1615/1616 and the FTC textile, wool and care-labelling rules (Parts 300, 303, 423). I also opened CPSC's 16 CFR Part 1107 on eCFR. I did not check lead content limits (Federal Hazardous Substances Act § 1278a), the component-testing rule (Part 1109) or the certificate rule (Part 1110).

1. Certificates (CPSA § 14, 15 U.S.C. 2063)

All clothing (General Certificate of Conformity)Children's clothing (Children's Product Certificate)
Testing basisA test of each product, or a reasonable testing program. An independent lab is optional unless CPSC requires one [77]Samples "shall" go to an accredited third-party conformity assessment body before import or distribution [77]
ContentEvery certificate must identify the issuer and any lab its testing relies on. It must give the date and place of manufacture and of testing, plus names, addresses, phone numbers and the records contact. It must be in English [77]Same
DistributionIt must travel with the product or shipment. A copy goes to each distributor or retailer, and to CPSC on request [77]Same
  • Penalties: failing to furnish a certificate, or issuing a false one, is a prohibited act. So is not meeting § 2063, including its tracking-label requirement [79].
  • No exemption from compliance: being certified does not excuse a product that does not actually comply [77].

2. Children's clothing: ongoing testing (16 CFR Part 1107)

These points come from the eCFR text of Part 1107.

  • Initial certification: send enough samples to give "a high degree of assurance" (§ 1107.20). If any sample fails, you must investigate before you can certify.
  • Periodic testing by a third-party lab (§ 1107.21): at least once a year by default. With a production testing plan, at least once every two years. If you use an ISO/IEC 17025-accredited lab for continuing testing, at least once every three years. You need a written plan for each product at each manufacturing site.
  • Material change: a change in design, process or component sourcing, including a new supplier, that could affect compliance means retesting and a new certificate (§ 1107.23).
  • Undue influence: you need a written policy, staff training with signed attestations, and a duty to notify CPSC (§ 1107.24). The Act also gives CPSC power to withdraw a lab's accreditation over undue influence [77].
  • Records: keep them for five years and make them available to CPSC (§ 1107.26).
  • Tracking marks: children's products need permanent marks on the product and its packaging, "to the extent practicable". The marks must show the manufacturer or private labeler, the location and date of production, and batch or run details [77].
  • Small batch relief: this applies only to firms with no more than $1,000,000 in gross revenue (CPI-adjusted) and no more than 7,500 units of the product in the previous year. They must register with CPSC first. The relief does not cover lead paint, small parts or the other early-schedule rules [77].
  • Phthalates: the 0.1% limits on DEHP, DBP and BBP apply to "any children's toy or child care article" [80]. That is the scope as the Act states it.

3. Flammability guaranties and records (Flammable Fabrics Act)

Part 1610 (all clothing textiles)

  • Why a guaranty matters: a guaranty received in good faith protects the holder from criminal prosecution. It must rest on "reasonable and representative tests" [81].
  • Testing program: anyone issuing an initial guaranty "shall devise and implement" a testing program [82]. The minimum is at least one test showing conformance. You decide how many tests and how often, and the tests may be done abroad or by another firm [83].
  • Records: keep them for 3 years [84]. Not keeping them counts as furnishing a false guaranty [85].
  • Foreign guarantors: a guaranty from a non-US resident cannot be relied on as a bar to prosecution [86].
  • Exempt fabrics: the fabric exemptions covered earlier (plain fabrics of 2.6 oz/yd² or more, and all-synthetic or wool fabrics) remove the need for testing to support guaranties.

Children's sleepwear (Part 1615; Part 1616 has parallel rules)

  • Records: the manufacturer, importer or converter "shall maintain" records that trace each production unit from manufacture to sale [87].
  • Unit identification: each item gets a GPU or FPU identification [88]. A garment production unit is up to 500 dozen garments [89].
  • Testing: prototypes are tested before production, and each unit is accepted or rejected [90]. Guaranty tests are the tests done under the Standard's sampling plan [91].
  • Tight-fitting garments relying on the exclusion need two things:
    • the "Wear Snug-fitting, Not Flame Resistant" label [92]
    • a yellow hangtag [93]

4. FTC labelling that needs supporting evidence

  • Fibre content and identity (Part 303): fibre content, country of origin and either the company name or its RN must be disclosed. Garments with a neck must show origin at the inside centre neck [94]. Stated fibre percentages may vary by no more than 3% of total fibre weight [95]. RNs are requested at rn.ftc.gov [96].
  • Wool products (Part 300): the label must give wool percentages, country of processing, and the manufacturer's name or RN [97][98].
  • Care labels (Part 423): a permanent care label is required [99]. The manufacturer or importer "must establish a reasonable basis" for the care instructions before sale [100]. Not having that basis is an unfair practice [101].

Optional label: a "Meets CPSC Safety Requirements" label may be used only on certified products, and it must not imply that CPSC endorsed the product (16 CFR 1107.30).

Q.04