Test Methods for Testing Flame Resistance of Children’s Clothes

There are various specific provisions for the flame resistance performance of fabrics in every country in the safety standards of children’s clothing. According to the standard, the flame resistance performance of the textiles is measured by the standards of products and the test methods respectively.

(1) Product standards
Products are requested to comply with the minimum requirements of quality or the upper limits for each index. For instance, there are different minimum requirements for the combustion performance of fabrics in the fire-retardant standards for children’s clothing in various countries.
(2) The test methods
The standards of the test have been established to regulate the test methods for obtaining the quality parameter without making any evaluations of the results. Despite being the same, the results from different test methods cannot be compared. In order to determine the criteria for flame resistance in various nations, it is necessary to take both the flame resistance value and test methods into account.

 The main test methods for flame resistance

It is well-known that we generally judge the flame resistance performance of most fabrics from the burning rate which refers to the combustion time, the degree of damage to the fabrics caused by the flame, and the lasting time for which the fabric retains flame after the flame has been extinguished.

There are numerous combustion test methods that adhere to different criteria. The relative position of the specimen and the flame allows us to categorize them as the vertical method, inclined method, and horizontal method. The stated specimen must be positioned vertically in accordance with the vertical method, which requires that its lengthwise direction be parallel to the horizontal line. In addition, the specimen must be ignited by the combustion source either below or on its surface. This method is mainly used to test the flame resistance performance of textiles, such as garment fabrics, decorative fabrics, tent fabrics, and so on.

1 Vertical Flammability Chamber

For the 45° inclined method, the required specimen must be positioned at a 45° angle. In other words, the specimen’s lengthwise direction should form a 45° angle with the horizontal line. Additionally, the specimen’s upper or lower surface must catch fire from the combustion source. This method is applicable to test the flame resistance performance of many different decorative fabrics in the interior of conveyance.

2 Forty-five Degree Flammability Tester

And the horizontal method is used to test the flame spread distance and time of the specimen which is placed horizontally and ignited, for testing the flame resistance performance of bedding fabrics like carpets and sheets.

3 Horizontal Flammability Tester

The usage of flame is a necessity in combustion tests. As a result, it is crucial that we accurately regulate the flame during the test. To put it another way, we must carefully regulate the flame’s length, ignition source, and ignition duration. The following are a few of the causes. The thermal value of the flame will make changes with different sources of ignition. And the length of time is in proportion to the thermal value. The former is longer, the higher is the latter. More importantly, the flame length must comply with the standard. It will be easier to burn the fabric if its flame length is long enough as it can contact the fabric more fully.

However, there is a huge limitation on the data obtained by traditional evaluation methods of flame-retardant performance of textiles. Sometimes, the test results will vary differently towards the same material if it is tested in diverse methods. We can observe that a single flame retardant test method typically falls short of accurately capturing the material’s burning characteristics. Therefore, we ought to employ a variety of test methods.

The difference in tests for the flame resistance performances of children’s clothing in different countries

1  Combustion method:

Chinese standard	Inclined method
American standard, European standard, British standard, and Australian standard	Vertical method

2  Ignition methods:

Standards	Ignition location	Method
American standard	The bottom	All apply the vertical combustion method
European Standard and British Standard	The surface

3  Combustion sources:

British standard	butane
American standard	methane
European standard	propane
Australian standard	propane or propane/butane gas mixture

4  Requirements for post-treatment:

Materials must be tested before and after being washed in the prescribed washing procedures according to American standards and Australian standards. The British insist on testing the material after washing while Europe merely demands testing the material before it is washed. Additionally, materials in China whose flame resistance performance is rated as Level 1 or 2 must undergo a test to determine their flame resistance performance.

5  Sampling procedures:

Upholding the principle of American standard, testers are requested to take the sample from both fabrics and garments while testers in Europe take samples respectively from the warp and weft direction of the fabrics. The Britain standard is more complicated and stricter. In addition, testers also must confirm what the sampling is belong to, fabric or garment. In contrast to strict Britain standards, the Australian standard only requires testers to take the sample from the area of the fabric or garment that runs their length and the Chinese standard only requires testers to do that from the area of the specimen that burns the earliest regardless of the type of materials.

6  Examining Indicators:

Chinese standard	burning rate
European standard	burning rate and surface flash
American standard	the length of carbonization after burning
Britain standard	the degree of flame spread and burning rate
Australian standard	burning rate and the time of burning on the surface

An introduction of the flame resistance performance test methods in different countries

1  American standard

As an illustration, the American CFR 16 Part in 1615 and the flammability standard for children’s sleepwear in 1616 both use the vertical method to test the flame resistance performance of children’s sleepwear, focusing primarily on detecting the length of sample carbonization within 3 seconds for fabrics in use. The standard requires that both the fabric and the finished garment for children’s clothing undergo a flame resistance performance test.

The steps listed below must be taken in order to test the fabric’s flame resistance performance. At first, prepare several samples (based on the total amount of fabric orders) and make 5 test samples for each sample (2 samples taken from the area in warp or weft direction, and the remaining 3 samples taken from areas in other directions). Then wash half of them at once and wash the remaining ones 50 times before testing their flame resistance performances. Keep in mind that the test sample cannot be obtained from an area that is too close to the cloth’s edge, and the five test samples should be taken from various locations within the same specimen.

It is crucial to test the seams and decorative elements of sample clothing for determining how well it resists flame. You must make three test samples and five test samples from each seam or decorative accessory for each group of testing. And the seam should be situated in the center of the test sample, paralleling the length direction. For the final garment, three more samples should be prepared and five test samples are required to be made at the area where the longest seam lies. A post-wash burning performance test of the garment is required if the post-wash burning performance test is not performed when the fabric maintains its shape.

Each test sample is 89 mm wide and 254 mm long in size. In the test, the specimen is suspended vertically on the holder. However, the seam test specimen needs to be placed in the center of the holder. Methane gas that is at least 97 percent pure should be used to fuel the combustion burner. The flame length is regulated to 3.8 cm, and the range of the air pressure is from 126 to 132 mm Hg. Finally, the specimen must be ignited from the center of its lower end for at least 2.8 seconds and a maximum of 3.2 seconds in order to determine the length of carbonization. Measured by the standard regulation, the average carbonization length of 5 test specimens is not allowed to exceed 7 inches, and each of them should be less than 10 inches.

2  EU standard

A document, named detailed procedures about the determination of burning performances of textiles and clothing fabrics released by EU EN 1103 proposes the vertical method to test the flame resistance performances of children’s sleepwear, mainly testing the surface flash and burning rate of the fabric. We must test three specimens taken from the area where the warp and weft of the fabric are located and can not wash them prior to the test in accordance with the standard of burning performances of children’s sleepwear in EU EN 14878.

Each test sample is 170 mm wide and 560 mm long in size. In the test, the specimen is suspended vertically on a holder. Then the first marker line is placed at the distance of 220 cm and the third marker line at 520 mm away from the igniter. Next, at the bottom of the holder, a piece of medium-density filter paper is placed vertically 55 or 45 mm away from the filter paper. The burner is filled with propane which can burn for 10.2 or 9.8 seconds. It is ignited on the surface of the fabric with the igniter 20 mm away from the bottom of test specimens and 16 or 18 mm horizontally distancing from the surface of the test specimen. And the flame should be close to the test specimen with a flame length of 23 or 27 mm horizontally. In this process, we need to record the burn-off time of the first marker line as well as the third marker line respectively, and whether there is a surface flash and the filter paper is ignited.

On a basis of the standard requirements of children’s sleepwear burning performance published by the EU EN 14878, there is no need for the producers to design the surface flash on children’s clothing (non-sleepwear) and the burn-off time of the third mark line with a length of 520 mm is not less than 15 seconds. And there is also no need for the producers to design the surface flash on children’s sleepwear and the burn-off time of the third mark line with a length of 520mm is not less than 10 seconds.

3  British standard

The essay on the test method flammability of textile fabrics when the vertically oriented specimen is subjected to a small flame on the surface or edge of its bottom released on British BS 5438 talks about using a vertical method to test the flame resistance performance of children’s pajamas, mainly figuring out the burning rate of the fabric. The standard mandates that three test samples should be separately tested in areas of fabrics’ warp and weft.

There are three test methods in BS 5438. You can better understand the functions of TEST 1, TEST 2, and TEST 3 through the below table.

TEST 1   TEST 2   TEST 3	Purpose of the test	Ignition time
	ignition time	A: ignite the surface of the specimen   B: ignite at the bottom of the specimen
	the degree of flame spread and damage to the fabric
	the burning rate of the flame

TEST 2A and TEST 3A methods are used to test the flame resistance of children’s clothing.

1  TEST 2A method

When applying the TEST 2A method, we must use the specimen with a width of 160 mm and length of 200 mm in size and suspend it vertically on the gripper. The burner is filled with butane and can keep burning for 10 seconds. Before starting, we should place the igniter in an area where it is 20mm away from the bottom of the specimen. We also need to ensure that the flame length should be 38 mm or 42 mm when they are hung vertically. And then we need to place the igniter horizontally and take it to approach the test specimen slowly, ensuring that the horizontal distance between the igniter and the surface of the test specimen should be 16 mm or 18 mm. In this process, we need to record the flame spread time, the shade ignition time of the flame, and whether there is a burning residue. We also need to examine whether the edges of flame make any contact with the upper boundary of the specimen or the vertical boundary of both sides and whether there are edges of flames or holes extending to the upper boundary or the vertical boundary of the two sides of the specimen.

2  TEST 3A method

When applying the TEST 3A method, we must use a specimen with a width of 170 mm and a length of 560 mm in size and suspend it vertically on the gripper. The first mark line should be placed at a distance of 210 mm, the second one 360 mm, and the third one 510 mm away from the ignition point. The burner should be filled with butane and can keep burning for 10 seconds. We also need to ensure that the flame length should be 38 mm or 42 mm when they are hung vertically. Then we need to place the igniter horizontally and take it to approach the test specimen slowly, ensuring the horizontal distance between the igniter and the surface of the test specimen is 16 mm or 18 mm. The burn-off time of each marker line should also be recorded.

There are three categories of the flame resistance performance of fabrics in children’s clothing based on the standard in BS 5722.

Level 1: When the test is carried out according to Test 2A released in BS 5438:1989, no portion of any hole or the lower limit of any flame should make contact with the upper edge or vertical edges of any specimen. In addition, the average time of delayed ignition and afterglow should not exceed 4.0 seconds.

Level 2: When the test is done in accordance with Test 2A released in BS 5438:1989, a test specimen shall be classified as Level 2 if any part of the hole or the lower limit of any flame makes no contact with the upper edge or vertical edge of any specimen. If any specimen fails to meet this requirement, six specimens shall be tested once again in accordance with Test 2A in BS 5438:1989. Any part of the hole or the lower limit of any flame is not allowed to contact with an upper edge or any vertical edge of any of the 6 specimens.

Level 3: When the test is done in accordance with Test 3A released in BS 5438:1989, six specimens shall be classified as Level 3 if the second mark line in the test is not broken within 30 seconds or the third mark line is not broken within 42 seconds. If any of the specimens do not meet this requirement, six specimens shall be tested in accordance with Test 3A in BS 5438:1989. If the situation is the same as what was mentioned before, they shall be classified as level 3.

The determination of flame spread about vertically oriented specimens and burning performance of textile fabrics in Australian ISO 6941 releases the vertical method to test the flame resistance performance of children’s sleepwear and the burning rate of vertically oriented specimens.

According to the determination of burning performances and the burning time on the surface of the fabric in ISO 10047, we can determine the burning time of the test fabrics which belong to pilling and pile fabrics. Children’s sleepwear and limited daily clothing produced to reduce the possibility of fire in AS/NZS 1249-2014 stipulates that the burning performance of the fabric before and after being washed should be tested and three test samples should be taken from the area in a longitudinal direction of the fabric or garment.

As required by the standard stipulated in the essay regarding the determination of flame spread about vertically oriented specimens and burning performances of textile fabrics in ISO 6941, we must use the specimen 170 mm wide and 560 mm long in size and suspend it vertically on the gripper. The first mark line should be placed at a distance of 220 mm away from the igniter, and the second one 520 mm. Then put a piece of density filter paper at the bottom of the holder and place the test sample at a distance of 45 or 55 mm vertically away from the filter paper. The burner should be filled with propane or a mixture of propane and butane and can keep burning for 9.8 or 10.2 seconds.

Children’s sleepwear and limited daily clothing produced to reduce the possibility of fire in AS/NZS 1249-2014 stipulates that we should ignite the surface of fabrics, with the igniter 20 mm away from the bottom of the specimen and the flame approaching the bottom of the specimen horizontally with a length of 23 or 27 mm. The igniter should also be placed at a horizontal distance of 16 or 18 mm away from the test sample. In this process, we need to record the burn-off time of the first mark line and the third mark line, whether the filter paper is ignited, and the length of the part of the specimen burned if the filter paper is ignited.

According to the determination of burning performances and the burning time on the surface of the fabric in ISO 10047, four test specimens taken from the area in warp and weft directions of the fabric should be measured respectively and each test specimen is loaded with a width of 75 mm and length of 170 mm and hung vertically on the gripper. The burner should be filled with butane or a mixture of butane and propane and can keep burning for 0.9 or 1.1 seconds. We also need to ensure that the flame length should be 38 mm or 42 mm in the vertical direction. Then we need to place the igniter horizontally and take it to approach the test specimen slowly, ensuring the horizontal distance between the igniter and the surface of the test specimen is 15 mm. Finally, observe whether there is spread flame or fluffy being ignited. If that does happen, record the burn-off time of the marker line which is placed under the ignition point away from 75 mm.

Children’s clothing can be divided into four categories stipulated by Children’s sleepwear and limited daily clothing produced to reduce the possibility of fire in AS/NZS 1249-2014.

(1)The burning time of the fabric where the flame spreads from the first marker line to the third marker line can not be less than 12 seconds, and the ignition time of each test sample must be more than 10 seconds. If the fabrics are molten and drop down to ignite the filter paper when being burned, the length of the burned filter paper shall not be more than 20mm. The burning time of the surface of suede fabrics washed shall not be less than 10 seconds.

(2)The burning time of the surface of suede fabrics washed can not be less than 10 seconds.

(3)The burning time of the surface of suede fabrics washed is not less than 10 seconds. Cellulose fiber, acetate, and acrylic fiber products are prohibited to use in this type of children’s clothing. For the fabric not to pass the burning rate test of the first kind of children’s clothing, the content of cellulose fiber, acetate, and acrylic fiber in the fabric should be less than 50%.

In China, we use the tilt method to test the burning performances of children’s clothing fabrics, mainly for the burning rate of the fabric placed at a 45-degree angle when it is tilted at a 45-degree angle in accordance with the standard outlined in the GB/T 14644-2014 essay on determining the burning rate of textile fabrics at a 45-degree angle. The standard stipulates that five test samples should be tested. The location of the length direction of the specimen depends on in which direction the fabrics can burn at the highest rate. If the direction of the fastest burning rate of the fabric is unknown, the location of the length direction of the specimen depends on in which direction that fabrics can burn at the highest rate in the pretest. If warp and weft burning rates are the same as the non-suede fabric specimens in the pretest, the warp can be regarded as the length direction. The specimen is loaded with a width of 50 mm and length of 160 mm and should be hung at an angle of 45 °C on the gripper. The burner is filled with butane and can keep burning for 0.95 or 1.05 seconds. We also need to ensure that the flame length should be 16 mm. Then we need to place the igniter at the distance of 19 mm and a marker line 127 mm away from the ignition point. In the test, we need to place the flame vertically on the surface of the specimen and record the burn-off time of the marker line. For suede fabrics, the specimen should continue to burn to determine if the base fabric keeps burning and melting.

Burning performance can be divided into three grades according to the standard proposed in the essay textile fabrics – flammability – determination of the burning rate at a 45-degree angle.

Number of specimens		Flame spread time		Class of flammability
5	Non-suede textiles	The specimen is not ignited/the marker line is not burned off		Class 1 (normally combustible)
		As long as exist	≥3.5 s	Class 1 (normally combustible)
			< 3.5 s	Test 5 more pieces
	Suede textiles	The base cloth is not ignited. And the flame spread time is not considered.		Class 1 (normally combustible)
		The specimen is not ignited. / the marker line is not burned off.		Class 1 (normally combustible)
		Only one	<4s, the base cloth is not ignited; ≥4s, the base cloth is not considered	Class 1 (normally combustible)
			<4s, while the base cloth graded as class one is ignited	Measure 5 more pieces
		2 and above	0s only one flash Fire on the surface of the fabric >7s, take no consideration of the base cloth 4s≤ t≤7s, 1 piece of base cloth is ignited <4s, 1 piece of base cloth is ignited	Class 1 (normally combustible)
			4s≤ t≤7s,  2 or more pieces of base cloth are ignited	Class 2 (moderately combustible)
			<4s,  2 or more  pieces of base cloth are ignited	Measure 5 more pieces
10	Non-suede textiles	Only one		Class 1 (normally combustible)
		2 and above	≥3.5s	Class 1 (normally combustible)
			<3.5s	Level 3 (fast and violent burning)
	Suede textiles	Only one		Class 1 (normal combustible)
		2 and above	>7s, take no consideration of the base cloth 4s≤ t≤7s, at most 2 pieces of base cloth are ignited <4s, at most 2 pieces of base cloth are ignited	Class 1 (normally combustible)
			4s≤ t≤7s, 3 or more pieces of base cloth are ignited	Class 2 (moderately combustible)
			<4s, 3 or more  pieces of base cloth are ignited	Class 3 (burning fast and violently)

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