Cotton phenolic Grade L is a thermoset laminate reinforced with fine-weave linen fabric impregnated with phenolic resin and cured under heat and pressure into rigid sheet, rod, and tube stock. As an l rod and sheet material governed by NEMA LI-1, Grade L is the standard choice in the cotton phenolic family when a smooth surface finish and superior machinability — rather than raw impact toughness — are the primary design requirements.
Grade L delivers 35,000 psi tensile strength, 23,000 psi flexural strength, and 14,000 psi compressive strength with a Rockwell M105 hardness and low water absorption of 1.04% over 24 hours. Maximum continuous operating temperature is 255°F (125°C). The fine linen weave produces a tight, uniform surface that reduces tooling wear and supports precise thread cutting, making l material ideal for gears, threaded inserts, precision bushings, cams, and intricate machined components.
Standards. Grade L is governed by NEMA LI-1. Flammability is rated 94HB per UL 94. Test methods follow ASTM D709 for laminated thermosetting materials. NEMA L designation confirms the fine-linen reinforcement that distinguishes this grade from canvas grades C and CE.
Sister grades. Choose Grade LE — linen phenolic, electrical grade when your precision-machined part also needs reliable dielectric insulation for terminal boards, switchgear, or electrical housings. Step down to Grade C — canvas phenolic when maximum impact strength and lower cost take priority over surface finish. For electrical canvas parts, see Grade CE.
