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Flame retardant resin, also known as fire-resistant resin, is a type of polymer material specifically formulated to resist ignition and inhibit the spread of flames. The purpose of flame retardant resins is to reduce flammability and slow down the burning rate of the materials they are incorporated into.


Different types of flame retardant additives are used in resin formulations, including halogenated compounds, phosphorus-based compounds, nitrogen-based compounds, and mineral fillers. They release flame-inhibiting gases, form a protective char layer, or interrupt the combustion process. The specific mechanism varies depending on the flame retardant additives used and the resin matrix.

Advantages and disadvantages of each type come down to fire performance, environmental impact, and processing requirements. 

  • Phosphorus-based flame retardants, such as phosphates or phosphonates, are commonly used in flame retardant resins. They can work by forming a protective char layer on the material’s surface, which acts as a barrier to heat and oxygen, thus slowing down the combustion process.


  • Nitrogen-based flame retardants, like melamine or melamine derivatives, release inert gases with heat exposure, diluting the oxygen concentration and suppressing the flame.


  • Mineral fillers, such as aluminum hydroxide or magnesium hydroxide, work by absorbing heat during combustion and releasing water vapor, which helps cool down the material and prevent the spread of flames.


  • Halogenated flame retardants, such as brominated or chlorinated compounds, have traditionally been widely used due to their effectiveness. However, they have raised concerns about their potential toxicity and environmental persistence. As a result, there has been a shift towards developing more environmentally friendly alternatives- Inquire about Formlab’s new Halogen-free Flame Retardant Resin.


It’s important to note that the choice of flame retardant resin depends on the specific requirements of the application, including fire safety regulations, environmental considerations, and performance criteria. It is commonly used in various applications for industries such as aerospace, automotive, electronics, construction materials, electrical and electronic devices, automotive components, textiles, and more. Different industries and regions may have specific standards and regulations governing the use of flame retardant materials.


Flame Resistant Material and Additive Manufacturing

Formlabs adds to their extensive Resin Library with new Flame Resistant resin. The favorable flame, smoke, and toxicity (FST) ratings are crucial in applications where fire safety is a concern. These ratings imply that FR Resin performs well when exposed to fire, produces minimal smoke, and exhibits low toxicity, making it suitable for use in environments to mitigate fire risk where people or sensitive equipment may be affected.

With that comes new opportunities with additive manufacturing for industries such as aerospace, electrical and airplane, automobile, and railway interior parts, protective and internal consumer electronics components, and custom jigs, fixtures, and replacement parts for industrial environments.


Product Description: Flame Retardant (FR)Resin is a self-extinguishing, halogen-free, certified UL94V-0SLA material with favorable flame, smoke, and toxicity (FST) ratings. It offers a 2.9 GPa tensile modulus (elasticity) and a heat deflection temperature (HDT) of 112 °C @ 0.45 MPa (pressure).


In the context of 3D printing, “halogen-free” refers to materials or resins that do not contain halogen elements such as chlorine (Cl), bromine (Br), or fluorine (F). Halogen-free formulations are sought after for a variety of reasons, including environmental concerns, health and safety considerations, and regulatory requirements.


When exposed to high temperatures, halogen-based compounds can release corrosive and toxic gases, which can be harmful to human health and the environment. By eliminating halogens, Formlabs FR Resin contributes to better fire safety and reduced toxicity.


The ability to 3D print with Formlabs Flame Resistant Resin offers several advantages-

First, 3D printing allows for complex geometries and intricate designs that may be difficult or impossible to achieve with traditional manufacturing methods.


Second, the high part quality ensures that the printed components meet the required specifications and have reliable mechanical properties.


Lastly, the high creep resistance of FR Resin and heat resistance ensures that the printed parts maintain their dimensional stability and structural integrity even under prolonged mechanical stress or elevated temperatures.


Overall, FR Resin is a versatile and reliable material for 3D printing flame-retardant parts, and provides a combination of fire safety, heat resistance, and processability, making it a suitable choice for manufacturing parts that need to withstand challenging environments while allowing for additional post-fabrication operations and optional post-processing steps.


When working with flame retardant resins for 3D printing, it’s crucial to follow Formlabs guidelines, including printing parameters, post-processing requirements, and safety precautions. Additionally, it may be necessary to comply with industry-specific fire safety standards and regulations for the intended application of the 3D-printed parts.


Always reference the Safety Data Sheet in accordance to OSHA Hazard Communication Standard, 29 CFR 1910.1200 as of March 2023.


Formlabs Flame Resistant Certifications

Flame Retardant Resin is UL94 V-0 and FAR25.853 certified.

Formlabs is UL 94 V-0 certified and has test data on FAR 25.853 Appendix F, Part I (a) (1) (ii)12 seconds Vertical Burn as well as smoke (ASTM E662) and toxicity tests (BSS 7229).


Flame Retardant (FR) Resin’s self-extinguishing properties and UL94 V-0 certification indicate that it has undergone rigorous testing and meets high safety standards. The UL 94 V-0 rating is achieved for a minimum wall thickness of 3mm.


The following table contains additional correspondence between FAR, Airbus, and Boeing standards.


Formlabs Printer Compatibility with FR Resins


New Formlabs Flame Retardant Resins are compatible with the following printers: 


It is also compatible with the listed Formlabs Resin Tanks:

  • Form 3/3B Resin Tank V1
  • Form 3/3B Resin Tank V2
  • Form 3/3B Resin Tank V2.1
  • Form 3L/3BL Resin Tank V1
  • Form 3L/3BL Resin Tank V2


Use Formlabs Flame Retardant Resins with the build platforms: 

  • Form 3 Build Platform
  • Form 3 Build Platform 2
  • Form 3L Build Platform
  • Form 3L Build Platform 2


Note: Print settings for this material may not be available yet on Form 3L and Form 3BL printers. Talk to an EAC expert for additional support.


Special Workflow Considerations

Formlabs experts highly recommend shaking the resin cartridges vigorously while rotating occasionally for at least 2 minutes before starting your first print. Failure to do so may affect the flame retardancy properties of your printed parts. If it has been more than 2 weeks since your last print, shake the cartridge again for 2 min and stir the resin in the tank before printing.


The resin is viscous, so allowing it to automatically dispense into a new tank for the first time before printing will result in a printer timeout error. Instead, please follow the instructions for manually pre-filling the resin tank before printing.


Due to the viscosity of Flame Retardant Resin, Formlabs recommends priming a new resin tank to reduce print time and avoid tank fill error messages.

  • Priming a Form 3: Unscrew the vent cap at the top of the cartridge and manually pour around 350 ml of the resin into the new resin tank bank.

  • Priming a Form 3L: Unscrew the vent cap at the top of the cartridge and manually pour the contents of one full cartridge of resin into the new resin tank.

The parts made from the flame-retardant resin can undergo optional post-processing steps like painting or electroplating. This offers flexibility in terms of the final appearance or functionality of the parts, as they can be customized to meet specific requirements.


Sanding or polishing to create a smoother surface by removing scratch marks can be done after the post-cure. Sanding with 600-grit sandpaper is sufficient to remove support nubs. Using a lower grit may additionally abrade the surface. For a smoother finish, higher-grit sandpaper up to 3000 grit can be used. Alternatively, polishing wheels combined with a rotary tool can be used for a quicker and even surface finish.


It is important to note that priming or polishing the surface of parts printed with Flame Retardant Resin with mineral oil or other flammable lubricants may invalidate the UL flammability rating.


Additionally, small negative features may be difficult to fully clean due to the resin’s high viscosity. Make sure to clean your parts thoroughly before post-curing! Consider using pressurized air for better cleaning.



Want to see in person how the parts self-extinguish? Visit us at our CXC in Minneapolis to get hands-on with multiple printed samples.