Rigid Urethane Foam

  • AVAILABILITY: Call for special Volume Discount Terms

  • SIZES:      4ft. x 8ft.       4ft. x 10ft.       5ft. x 8ft           5ft x 10ft.

  • THICKNESS: 1/2" to 20"

  • DENSITIES: 4 - 6 - 8 - 10 - 12 - 15 - 18 - 20 - 30 - 34 - 40 - 48 - 60 - 70 - 75 lbs. pcf.

  • Available in a service temperature of 300o F and 200o F

NC PROOFBOARD® a rigid urethane board, is used by aerospace, machine shops, model artists, boat builders and sign fabricators. The uniform cell structure of the high density light weight foam, is water resistant or water proof depending on the foam density. Excellent for exterior use as painted signs. The material is fast and easy to machine for making patterns, models and prototypes and to use in place of wood in boat construction. Used under heavy pipes as support and insulation. Main use is for composites & tooling.

It is your responsibility to make thorough tests of your methods and materials and temperature to insure success.​

​Important heat curing guideline: The vacuum bag or autoclave pressure must not exceed 20 PSI. 

Temperature: Start the oven at an ambient room temperature before putting in the NC PROOFBOARD® foam. Do NOT preheat the oven. Ramp the oven temperature up at 1o per minute and down at 2o per minute. Warping or cracking may occur if this oven ramp up and down is not followed.


A major use for NC PROOFBOARD® is proofing CNC machining paths and milling details, composites & tooling. The nonabrasive rigid urethane foam board is a perfect choice. The 15 lb. density is for proofing. It is less expensive than Machineable Plastic, poly boards, metal and most other plastics. Some advantages are:

  1. Reduced overall flow-time required to proof the CNC. This enables the machine to operate up to 100% of its feed rate during most of the proofing operations. Manufacturer's records show that maximum feed rates can be achieved during 75% to 80% of all proof machining.

  2. Nonabrasive material saves on tool changes.

  3. Coolants are not required during machining.

  4. In the event an error is made during programming, which could cause the cutting head to make an extreme movement, the NC PROOFBOARD® having a lower density than metal, will allow the cutter to crush it rather than ruining the cutter or damaging the machine spindle, bearings, preset adapter or tool holder.

  5. NC PROOFBOARD® is reasonably stable and can be dimensionally measured. It does not melt with cutting friction. It is lightweight and can be easily handled.

  6. Multilevel proofing can be done on thicker boards for flat products such as wing skins. Proof once, check measurements, mill level, proof again, repeat as needed. Have a vacuum pickup near cutting head to remove air born dust. Put oversized plastic tarp down first, then place the NC PROOFBOARD® on top. When the machining is finished, remove the cut foam board. Gather the four corners of the tarp and remove the dust to a fire safe storage container.

The foam can be patch repaired using our R1 FAST CAST® resin and #M15 FILLER and re-machined in a couple of hours. Bonding can be done with #BOND 101. If you need a higher strength bond, use our EPOXY RESIN or EPOXY PUTTY. For CNC proofing, we recommend 15-D.


Use NC PROOFBOARD® as a core then build up to the finished shape using clay. This can save labor time and material. Suggest 6-D or 10-D.


The foam board can be sandblasted, routed, carved, sawed and drilled. Filling and smoothing compounds are available to use prior to finish painting. Excellent for exterior use. Suggest 15-D or 18-D. More complete ideas and  instructions come with the brochure.


If you want a dense, 48 lbs. pcf., very smooth cell structure in a custom shape and size, without having to apply sealer coats prior to painting, ask about our BUTTER-BOARD®


The foam board resists moisture and is not affected by fungus or mildew. It has no food value for vermin and insects. This material has a high chemical resistance and is not affected by most solvents and chemicals with the exception of the chlorinated solvents. For exterior uses, UV protection should be applied with a suitable coating. Excellent strength-to-weight ratio makes this material an ideal replacement for wood, metal and other plastics. Engineers and designers should familiarize themselves with this material in order to have more appreciation for its overall capabilities. Find out for yourself just how good this cost saver really is, how easy it is to use and what a time saver. 


 Interior foam applications must be protected with a fire barrier coating equivalent to one-half inch gypsum plaster or gypsum board heat resistance or an approved sprayable barrier coating (check with your local building regulations in case they are different). Urethane foam is an organic material and will burn under the right conditions of oxygen and heat. This material is NOT fire proof.

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To meet your other needs for custom shapes and sizes, tooling and prototypes, refer to the Machineable Plastic section.          Email Address: