| ASTM or UL TEST | PROPERTY | SP-1 | SP-21 |
| | Filler Material | Unfilled | 15 % Graphite |
| D792 | Density (lb/in³) | 0.051 | 0.055 |
| (g/cm³) | 1.43 | 1.51 | |
| D570 | Water Absorption, 24 hrs (%) | 0.24 | 0.19 |
| D638 | Tensile Strength (psi) | 12,500 | 9,500 |
| D638 | Tensile Modulus (psi) | N/A | N/A |
| D638 | Tensile Elongation at Break (%) | 7.5 | 4.5 |
| D790 | Flexural Strength (psi) | 16,000 | 16,000 |
| D790 | Flexural Modulus (psi) | 450,000 | 550,000 |
| D695 | Compressive Strength (psi) | 19,300 | 19,300 |
| D695 | Compressive Modulus (psi) | 350,000 | 420,000 |
| D785 | Hardness, Shore D | E45-60 | E25-45 |
| D256 | IZOD Notched Impact (ft-lb/in) | 0.8 | 0.8 |
| Poisson's Ratio | 0.4 | 0.4 | |
| D696 | Coefficient of Linear Thermal Expansion (x 10^-5 in/in/˚F) |
3 | 2.7 |
| D648 | Heat Deflection Temp (˚F/˚C) at 264 psi | 680/ 360 | 680/ 360 |
| | Max Operating Temp (˚F/˚C) | 500/ 260 | 500/ 260 |
| C177 | (BTU-in/ft²-hr-˚F) | 2 | 6 |
| | (x 10^-4 cal/cm-sec-˚C) | 6.9 | 20.7 |
| UL94 | Flammability | V-0 | V-0 |
| D149 | Dielectric Strength (V/mil) short time, 1/8" thick | 560 | 250 |
| D150 | Dielectric Constant at 1 MHz | 3.55 | 13.2 |
| D150 | Dissipation Factor at 1 MHz | 0.0034 | 0.0106 |
| D257 | Volume Resistivity (ohm-cm) at 50% RH | 10^14-15 | 10^12-13 |