Horizontal flammability testing for children's toys evaluates whether toy materials ignite and propagate flame at hazardous rates, as mandated by ASTM F963 and the test method described in 16 CFR 1500.44. This guide explains the test principle, sample requirements, procedures, evaluation criteria, and practical applications that toy manufacturers, importers, and quality engineers need to understand. Working with accredited third-party laboratories ensures reliable results that support regulatory compliance in global markets.
Technical Overview
Horizontal flammability testing, also known as the horizontal burn test, is a fire-safety evaluation method used to determine whether materials used in children's toys ignite easily and burn at a dangerous rate. In this test, a bar-shaped specimen is mounted in a horizontal orientation, one end is exposed to a controlled flame, and the behavior of the material is observed after the ignition source is removed. Materials that continue to burn and propagate the flame front rapidly along the specimen are considered hazardous and non-compliant.
The primary regulatory basis for this test in the United States is ASTM F963, the Standard Consumer Safety Specification for Toy Safety, which requires that toys shall not be composed of materials that, when tested in accordance with the method described in 16 CFR 1500.44, burn at a rate exceeding 0.1 inch (approximately 2.5 mm) per second. This method was originally developed under the Federal Hazardous Substances Act (FHSA) to identify extremely flammable solids, such as celluloid plastics, and it remains a mandatory requirement for toys sold in the U.S. market under federal law.
It is important to distinguish the horizontal bar method from the flammability requirements in other jurisdictions. European standard EN 71-2, international standard ISO 8124-2, and Chinese national standard GB 6675-3 focus on flame-spread behavior of specific toy categories, such as toys worn on the head, dress-up costumes, toys intended to be entered by children, and soft-filled toys, using small-flame application to surfaces or edges. The horizontal burn test, by contrast, evaluates the bulk burning rate of solid toy materials.
- ASTM F963 – Standard Consumer Safety Specification for Toy Safety (flammability clause referencing 16 CFR 1500.44)
- 16 CFR 1500.44 – Test method for determining extremely flammable solids under the FHSA
- 16 CFR 1500.3 – Definitions of flammable and extremely flammable solids
- EN 71-2, ISO 8124-2, GB 6675-3 – Regional and international toy flammability standards with complementary test approaches
Testing Samples
Cut Strips from Finished Products
When the toy or one of its components is large enough, the preferred approach is to cut a test strip directly from the finished product. The typical specimen is a bar approximately 6 inches (152 mm) long and 0.5 inch (13 mm) wide, with the native thickness of the article, up to a maximum of about 0.5 inch. Testing the actual production material provides the most representative assessment, because it captures the effects of pigments, additives, surface finish, and processing conditions used in manufacturing.
Prepared Material Test Bars
When a toy is too small, too curved, or otherwise unsuitable for cutting a strip, test bars are prepared from the same raw material used in production. The material is molded, cast, or extruded into the standard bar dimensions using the same formulation, colorants, flame retardants, and processing parameters as the actual product. This ensures the laboratory results reflect real-world burning behavior of the toy material.
Sample Quantity and Selection
Multiple specimens, typically a minimum of three per material, are tested to account for variability between samples. Every distinct polymeric material in the toy should be evaluated, including different colors and formulations, since additives and pigments can significantly alter burning behavior. Special attention is given to materials with a known history of high flammability, such as cellulose nitrate (celluloid) plastics, and to combustible metals or alloys, such as those containing magnesium, which are also covered by the regulatory scope of the method. When submitting items to accredited third-party laboratories, manufacturers generally provide complete toys together with spare material for specimen preparation.
Testing Items
The horizontal flammability test generates several key data points that together determine whether a toy material complies with safety requirements:
- Ignition behavior – whether the specimen ignites under standardized flame exposure conditions
- Afterflame characteristics – how the material behaves immediately after removal of the ignition source
- Flame propagation rate – the calculated burning rate of the flame front along the specimen, expressed in inches or millimeters per second
- Self-extinguishing performance – whether the flame extinguishes on its own before traversing the measurement zone
- Compliance determination – comparison of results against the maximum allowable burning rate of 0.1 inch per second
- Ancillary observations – dripping of flaming particles, melting behavior, smoke generation, and glowing combustion
Testing Methods
Specimen Preparation and Marking
Specimens are prepared as described above and marked with reference lines that define a measured gauge length along the bar. These marks allow the technician to time how long the flame front takes to travel a known distance, which is the basis for calculating the burning rate. Specimens are conditioned in a controlled environment before testing to ensure consistent temperature and moisture conditions across the sample set.
Apparatus and Test Environment
The test is performed inside a draft-free fume hood or enclosed chamber at room temperature to prevent air currents from influencing flame behavior. The ignition source is a propane gas burner or torch adjusted to produce a blue flame of defined length, applied to the free end of the horizontally clamped specimen. A precision timer, a clamping fixture that holds the bar level, and appropriate safety shielding complete the standard setup.
Ignition Procedure
The specimen is clamped horizontally with one end exposed. The flame is applied to that end for the standardized exposure period, or until the specimen ignites. Once ignition is achieved, the ignition source is withdrawn, and the combustion of the specimen proceeds under its own sustained flame. Specimens that do not ignite during the exposure period are recorded as non-ignitable for that trial.
Measurement and Evaluation Criteria
After removal of the ignition source, the technician records whether the flame self-extinguishes or propagates. If the flame front travels between the reference marks, the elapsed time is recorded and the burning rate is calculated as distance divided by time. Specimens that stop burning before the flame front traverses the gauge length are classified as self-extinguishing, which is a compliant result. A material whose burning rate exceeds 0.1 inch (2.5 mm) per second is considered hazardous, and toys containing such materials fail the requirement. Results are reported for each specimen together with the calculated rate, ignition observations, and a clear pass or fail conclusion. Where specimens show varying behavior, the worst-case result governs the compliance decision.
Applications
Horizontal flammability testing supports toy safety at every stage of the product lifecycle, from material development to market surveillance. Typical applications include:
- Mandatory compliance testing for toys sold in the United States, where ASTM F963 is a federal requirement and test reports from accredited third-party laboratories are needed for certification
- Import documentation and customs clearance support, demonstrating that shipped products meet applicable flammability limits
- Material screening during product design, allowing engineers to compare resins, additives, and flame-retardant formulations before tooling investment
- Incoming quality control and production monitoring of plastics, masterbatches, and molded components
- Verification of supplier declarations and evaluation of material substitutions or cost-reduction changes
- Failure analysis and technical support in investigations of fire incidents involving children's products
FAQ
Which toys are subject to horizontal flammability testing?
The requirement applies broadly to toys intended for children, focusing on the solid materials from which the toys are made. In practice, all distinct polymeric and other combustible materials in the toy should be evaluated, particularly plastics known for high flammability. Certain materials that fall under separate flammability regulations, such as textile fabrics used in wearing apparel, are typically addressed by other standards rather than this method.
What is the pass or fail criterion?
A material passes if it does not ignite, self-extinguishes after removal of the flame, or burns at a rate that does not exceed 0.1 inch (2.5 mm) per second. A burning rate above this limit, or sustained flaming propagation that continues across the specimen, constitutes a failure, and the toy cannot be placed on the market with that material.
What happens if the toy is too small to cut a test strip from?
When the finished article cannot yield a strip of the required dimensions, the laboratory prepares test bars from the raw material using the same formulation and processing conditions as production. The results from these prepared bars are accepted as representative of the toy material.
How does this test differ from EN 71-2 and ISO 8124-2 testing?
EN 71-2, ISO 8124-2, and GB 6675-3 evaluate flame-spread behavior on specific categories of toys, such as head-worn toys, disguise costumes, toys children enter, and soft-filled toys, by applying a small flame to a surface or edge and measuring the speed of flame spread. The horizontal burn test under ASTM F963 and 16 CFR 1500.44 instead measures the bulk burning rate of a material bar and compares it with a fixed limit. Toys sold in multiple markets may need to satisfy both types of requirements.
How many specimens are needed and how long does testing take?
A minimum of three specimens per material is customary, with additional specimens recommended when results vary or when multiple colors and formulations exist. Testing itself is quick, typically completed within a few working days once specimens are prepared and conditioned, though overall turnaround depends on sample preparation and laboratory scheduling.
Can component materials be tested before toy assembly?
Yes, and it is considered good engineering practice. Testing raw materials and molded components early in development identifies flammability risks before mass production, reduces the cost of remediation, and shortens the final compliance verification timeline.