Permatex® 81878 Ultra Copper® Maximum Temperature RTV Silicone Gasket Maker, 3 Oz


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SKU: 10077535
MFG: 81878


Permatex® Ultra Copper® is a single component, room temperature vulcanizing gasketing compound designed to provide reliable "formed-in-place" gaskets for mechanical assemblies. This material cures on exposure to moisture in the air to form a tough, flexible, silicone rubber gasket. The product resists aging, weathering and thermal cycling without hardening, shrinking or cracking. Designed for the higher temperature environments encountered in 4-cylinder, turbocharged, and high performance engines. Permatex® Ultra Copper® is the most advanced high performance, high temperature (up to 700 degree Fahrenheit intermittent) RTV gasket available. OEM Specified.

  • Size: 3 ounce, tube
  • For high operating temperatures common in 4-cylinder, turbocharged or high-performance engines
  • The most advanced, high temp RTV silicone gasket available
  • Sensor-safe, low odor, noncorrosive. Superior adhesion
  • Three times more oil resistant than conventional silicones; eight times more flexible than cut gaskets
  • Temperature range -65 degree Fahrenheit to 700 degree Fahrenheit (-54 degree Celsius to 371 degree Celsius) intermittent; resists auto and shop fluids and vibration
  • Carded.

Suggested Applications


  • Exhaust manifolds/headers, valve covers, oil pans, timing covers, water pumps, thermostat housings.


  • Exhaust header flanges, slip fit exhaust pipes, and muffler end caps.


  • Exhaust manifolds/headers, valve covers, oil pans, intake manifold end seals, water pumps, exhaust tubes.


  • High temperature resistance
  • Sensor safe, non-corrosive
  • Superior adhesion and flexibility
  • Replaces most cut gaskets
  • Improved oil resistance
  • Can be used as a gasket maker or dressing
  • Non-flammable, Non-toxic
  • Low odor.

Typical Applications

  • Exhaust manifolds
  • Thermostat housings
  • Valve covers
  • Timing gear covers
  • Water pumps
  • Differential covers.

Directions For Use

For assembly as form-in-place gasket

  • Remove all previous material from mating surfaces. Permatex® Silicone Stripper or Gasket Remover is recommended for most materials.
  • For best results, clean and dry all surfaces with a residue-free solvent, such as Permatex® Brake and Parts Cleaner.
  • Cut nozzle to desired bead size, 1/16" to 1/4" in diameter. An 1/8" bead is usually sufficient for most applications.
  • Remove cap, puncture tube or cartridge seal and attach extension nozzle.
  • Apply a continuous and even bead of silicone to one surface, first tracing the internal areas of the gasket configuration, then all surrounding bolt holes.
  • Assemble parts immediately while silicone is still wet. Secure or tighten to recommended torque specs.
  • Re-torque will not be necessary after the product has cured.

For assembly as gasket dressing

  • Repeat steps 1 thru 4 as in previous section.
  • Apply a thin film of silicone to one surface to be sealed.
  • Place the pre-cut gasket onto silicone film.
  • Apply a second thin to pre-cut gasket surface.
  • Remove any excess and assemble parts immediately.

Note: Product not recommended for use as a cylinder head gasket or head gasket sealant.

Storage of Unused Product

  • Create a "Silicone Plug" by allowing excess material to extend beyond the extension nozzle or aerosol tip to cure, sealing and protecting the remaining product from moisture. For reuse, simply remove the cured product from the tip.

For Cleanup

  • Remove uncured product from parts and hand-tools with Permatex® Fast Orange® Wipes or Fast Orange® Hand Cleaners. If skinned over, break film with a dry cloth to remove as much as possible. Remove the remaining material with Permatex® Gasket Remover.
  • Clean hands with a dry cloth or Permatex® Fast Orange® Hand Cleaner.

Properties Of Uncured Material

  • Chemical Type: Oxime silicone rubber
  • Appearance: Copper colored non-sag paste
  • Odor: Low odor
  • Specific Gravity: 1.05
  • Extrusion rate @ 25 degree Celsius, (grams/min): >300
  • Flash Point, degree Celsius (degree Fahrenheit): >93 (>200)

Typical Curing Performance

  • Permatex® Ultra Copper® Hi-Temp RTV Silicone Gasket cures on exposure to moisture in the air. The product dries tack free in one hour and fully cures in 24 hours. Cure times will vary with temperature, humidity and gap.

Performance Of Cured Material

After 7 days at 25 degree Celsius (77 degree Fahrenheit), 50% Relative Humidity

  • Hardness (Shore A): >26
  • Elongation, %*: >350
  • Tensile Strength, N/mm2 (psi)**: >1.4 (>203)

*Material will stretch 3.5 times its original length before breaking.
**Amount of force required to break material.

Typical Environmental Resistance

  • Continuous, degree Celsius (degree Fahrenheit): -54 to 316 (-65 to 600)
  • Intermittent, degree Celsius (degree Fahrenheit): -54 to 371 (-65 to 700)

Chemical / Solvent Resistance

  • The product retains effective properties in contact with automotive fluids, such as motor oil, transmission fluids, alcohol and antifreeze solutions. Note: Not recommended for parts in contact with gasoline.

General Information

  • This product is not recommended for use in pure oxygen and/or oxygen rich systems and should not be selected as a sealant for chlorine or other strong oxidizing materials.


  • Products shall be ideally stored in a cool, dry location in unopened containers at a temperature between 8 and 28 degree Celsius (46 and 82 degree Fahrenheit) unless otherwise labeled. Optimal storage is at the lower half of this temperature range. To prevent contamination of unused product, do not return any material to its original container.


1.0 lb