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Fine-Weave Cotton-Fabric Reinforced Phenolic Laminate (NEMA L)
Linen phenolic offers a smooth surface finish, excellent machinability, and reliable mechanical strength for precision components such as gears, bearings, and threaded parts.

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Material Overview
L sheet is the flat-panel form of NEMA Grade L cotton-phenolic laminate — a thermoset composite produced by laminating fine-weave cotton fabric with phenolic resin under heat and pressure into rigid, dimensionally stable flat stock. The fine cotton weave used in Grade L produces smoother machined surfaces and better electrical performance than the coarser Grade C and CE, making L sheet a balanced choice for small machined parts and light-duty electrical insulation.
L sheet delivers tensile strength of 18,000 psi, flexural strength of 20,000 psi, and compressive strength of 36,000 psi. Rockwell hardness reaches M105, shear strength is approximately 14,000 psi, and water absorption over 24 hours is approximately 2.5%. The material carries a UL 94HB flammability rating and operates continuously up to 250°F (121°C). These properties make L sheet a practical choice for small machined plates, terminal boards, pulleys, light-duty cams, and tooling fixtures where surface finish and machinability matter.
Standards & compliance. L sheet conforms to NEMA LI-1 Grade L and meets defense specification MIL-I-24768/15 (Type FBI). Test methods follow ASTM D709. Ready Plastics stocks L sheet in a range of thicknesses; custom cuts are available through our cut-to-size service.
Sister grades. For higher dielectric performance, Grade LE phenolic sheet uses an even finer linen weave. For higher impact resistance, Grade CE phenolic sheet uses a coarser cotton; for the lowest-cost cotton-phenolic, Grade C phenolic sheet is the standard choice. For higher mechanical strength and lower water absorption, see G-10 glass-epoxy sheet.
Technical Specifications
Typical values at 23°C / 50% RH. Values are nominal and not guaranteed; refer to lot-specific certificates of conformance for production parts.
Frequently Asked Questions
NEMA Grade L is a fine-weave linen-fabric phenolic laminate — a thermoset composite of linen fabric impregnated with phenolic resin. It provides 35,000 psi tensile strength, a smooth surface finish, and excellent machinability with low tooling wear. Grade L is governed by NEMA LI-1 and is the preferred choice for precision mechanical components such as gears, bearings, threaded parts, and cams.
Grade L uses a fine linen weave; Grade C uses a coarser canvas weave. The linen weave in Grade L produces a smoother surface finish and better machinability, making it preferred for intricate precision parts. Grade C offers higher impact strength and toughness at lower cost, making it better for heavy-duty mechanical components that see shock loading. Neither grade carries an electrical rating — for electrical performance, see Grade CE (canvas) or Grade LE (linen).
Ready Plastics stocks linen phenolic Grade L in sheet and rod form across a range of standard thicknesses and diameters. Phenolic l rod stock is particularly popular for turned parts such as bushings, spacers, and threaded components. Cut-to-size is available on every SKU — contact us or review the datasheet for current size inventory.
Yes. Grade L's fine linen weave makes it one of the most machinable grades in the cotton phenolic family. It cuts cleanly on conventional mill, lathe, and drill press equipment, accepts tapped holes without chipping, and holds tight dimensional tolerances in turned and milled components. Use sharp carbide tooling, moderate speeds, and dust extraction — phenolic dust is abrasive and should not be inhaled.
No. Both use fine linen weave reinforcement, but they serve different applications. Grade L is a general-purpose mechanical grade optimized for machinability and structural performance. Grade LE adds an electrical rating — it is designed for components that require both precision machining and reliable dielectric insulation, such as terminal boards and electrical bushings. If electrical insulation is not a requirement, Grade L is the more economical choice.
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