Last-A-Foam® Performance Core Series

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Flame Retardant Polyurethane


Flame-Retardant Polyurethane Foam

FR-3700 is a CFC-free, rigid, closed-cell, flame-retardant polyurethane foam available in densities ranging from 3 to 40 pounds per cubic foot. It exhibits a high strength-to-weight ratio due to its cellular structure and cross-linked resin. Because of its closed-cell structure, LAST-A-FOAM® FR-3700 has great resistance to water absorption, and will not swell, crack, or split on exposure to water. This series is non-abrasive and can be machined with standard high-speed steel (HSS) cutting tools. It can also be cut cleanly with water jets and traditional wood-carving tools. This flame-retardant polyurethane foam particularly supports the following industries.

Click here to download our FR-3700 series technical data sheets

Download our FR-3700 Product Data Sheet


FR-3700 meets the requirements of aircraft BMS 8:133. This rigid, polyurethane foam is comparable to the FR-6700 in strength, temperature resistance and flammability performance. However, the FR-3700 is tougher (less friable) for cutting crisper edges.

More about Aerospace Foam


High-density rigid polyurethane FR-3700 foam is used to simulate human bone as a test medium within the medical device industry.

More about Medical Foam


FR-3700 foams are chosen for nuclear material applications and transportation of extremely hazardous waste. When used as an impact- and fire-insulation liner in transport containers, FR-3700 can be engineered to provide the ultimate in fire and collision protection for hazardous cargo, outperforming wood and other polymeric materials. The FR-3700 formulation is specially designed to allow predictable impact-absorption performance under dynamic loading. At the same time, it provides an intumescent char layer that insulates and protects hazardous materials, even when exposed to pool-fire conditions.

In particular, our FR-3700 foam has a solid history of successful use in radioactive materials (RAM) transportation packages. The regulations governing RAM packages often require energy absorption of 30-foot free drops and exposure to a 1,475°F, 30-minute fire under accident conditions. Our FR-3700 series foam is one of very few materials that can support the RAM package design in mitigating both mechanical and thermal energy.

More about Nuclear Foam

View a demonstration of how the FR-3700 Performance Core Series protects nuclear cargo from impact on our YouTube page or download our research paper on polyurethane foam as an impact mitigation and flame retardant material.


Use LAST-A-FOAM® 3700 Performance Core Series for constructing durable, weatherproof radomes. Impervious to moisture and transparent to radio signals, they protect marine, aerospace and recreational microwave antennas. Their high Tg suits prepregs that cure at higher temperatures. Or, let our Production Services team fabricate completed radomes using fiberglass prepregs from your specs.


  • Stable and inert
  • Flame retardant
  • High strength-to-weight ratio from cross-linked resin
  • Resistant to most chemicals and solvents
  • Easily shaped with common woodworking tools
  • Performs well as wood replacement
  • Will not support fungal growth


  • Models and design prototypes
  • Composite core, especially where flame retardation is important
  • Honeycomb edge closeout for aircraft interior sandwich panels used in overhead storage bins, passenger cabin class dividers, galleys and lavatories
  • Radioactive materials (RAM) transportation packages
  • Impact- and fire-insulation liner for hazardous waste containers
  • Vacuum form dies and mold patterns
  • Artificial human bone test media
  • Core material for composite prostheses
  • Load bearing

Sizing Chart

ProductsDensity (lbs/ft3)HeightWidthLength
FR-3703  3 24 48 96
FR-3704  4 24 48 96
FR-3705  5 24 48 96
FR-3706  6 24 48 96
FR-3707  7 24 48 96
FR-3708  8 24 48 96
FR-3710  10 24 48 96
FR-3712  12 18 18 100
FR-3718  18 18 18 100
FR-3730  30 12 24 96
FR-3730  30 18 18 100
FR-3740  40 10 18 100
FR-3740  40 12 24 100

Shown are maximum standard stock sizes based on density. Custom sizes are available. Cut sizes are available from .125 inches (3.175 mm) up to standard stock heights as listed above.

ProductsDensity (kg/m3)HeightWidthLength
FR-3703  48 60 121 243
FR-3704  64 60 120 240
FR-3705  80 60 120 240
FR-3706  96 60 120 240
FR-3707  112 60 120 240
FR-3708  128 60 120 240
FR-3710  160 60 120 240
FR-3712  192 45 45 250
FR-3718  288 45 45 250
FR-3730  481 30 60 240
FR-3730  481 45 45 250
FR-3740  641 25 45 250
FR-3740  641 30 60 250

Shown are maximum standard stock sizes based on density. Custom sizes are available. Cut sizes are available from .125 inches (3.175 mm) up to standard stock heights as listed above.

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