Fish Paper (Vulcanized Fiber)

 In Thermoset Plastics

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Fish Paper Characteristics

Fish paper (vulcanized fiber) is a strong, flexible paperboard that has good mechanical properties. It offers excellent electrical insulating and arc quenching properties. It is a good choice for applications in which moisture is not a factor and where temperatures do not exceed 425 degrees F. It can be die cut and machined. See the chart below for details of fish paper’s material properties.

Get a QuoteFish paper is insoluble in ordinary solvents and is unaffected by ammonia, turpentine, naphtha, benzene, petroleum, alcohol and ether. As a thermoset plastic, it has superior bending qualities and is especially useful for armature slot insulation.

  • Flexible yet durable
  • Excellent insulating properties
  • Can be die cut or machined
  • Superior punching and forming qualities

Applications for Fish Paper

  • Motor and switch insulation
  • Washers
  • Coil insulation
  • Arc shields
  • Gaskets
  • Transformer insulation

Contact a Dielectric Manufacturing knowledge expert to discuss the use of fish paper for fabrication of your thermoset parts. Call 800-367-9122 or email

Fish Paper Material Properties

Properties Thickness (inches)UnitsCommercialElectrical
Specific Volume.062"cu. in./lb23.023.0
Tensile StrengthMD.062"psi1600018000
Modulus of Elasticity in TensionMD.062"psi x 10512.012.0
CD.062"psi x 1058.08.0
Flexural StrengthMD.062"psi1500015000
Compressive Strength.062"psi3500035000
Impact Strength - Izod EdgewiseMD.062"ft-lbs/in. notch2.02.5
CD.062"ft-lbs/in. notch1.82.0
Hardness - Rockwell R Scale.062"Divisions8070
Bond Strength - ASTM D-952.062"psi900900
Bursting Strength -Mullen.016"psi-325
Tear Strength - ElmendorfMD.016"grams-550
Dielectric Strength - Short Time.016"volts/mil230300
Arc Resistance - ASTM D-495.062"seconds80125
Thermal Conductivity - 149° FBtu/hr/ft2/°F/ft.0.1680.168
Specific HeatBtu/lb/°F0.4030.403
Heat Resistance - Continuous°F230 - 240230 - 240
Thermal Expansion x 10-5MDin/in/°F1.11.1
Dimensional Change per % change in Moisture ContentThick.%1.01.0
Water Absorption - 24 hours.062"%66.063.0
Coefficient of Friction - Fiber on Fiber0.160.16
Coefficient of Friction - Fiber on Smooth Cast Iron0.210.21
Flammability - ASTM D-635.062"in/mm0.50.5