MASTERS® PRO-BLUE® is a non-toxic, non-corrosive, non-hardening paste. It effectively seals both metal and plastic threaded connections. It will not dry out, stain, harden or separate. Lubricates during assembly and can easily be disassembled even after years of service. Sold by weight, not by volume.

MASTERS® PRO-BLUE® effectively seals most liquids and gases against leakage to 10,000 psi and from –200°F to +400°F (-129°C to +204°C).


  • Stir well.
  • Do NOT dilute.
  • Threads must be clean.
  • Apply to Male Threads beginning at second thread back.

MASTERS® PRO-BLUE® is recommended for:

  • Acids (dilute)
  • Air (compressed, gaseous)
  • Aliphatic Solvents
  • Alkalis (dilute)
  • Ammonia
  • Brine
  • Carbon Dioxide
  • Castor Oils
  • Caustic Alkali (dilute)
  • Corrosives
  • Diesel Fuel Oil
  • Gasoline
  • Heating oils
  • Helium (gaseous)
  • Hydraulic Oils
  • Inert Gases (gaseous)
  • Jet Fuel (JP4, 5 & 6)
  • Kerosene
  • Liquefied Petroleum Gases
  • Manufactured Gases
  • Mineral Oils
  • Natural Gas
  • Nitrogen (gaseous)
  • Oils
  • Petroleum Solvents
  • Potable Water
  • Propane
  • Refrigerants (most)
  • Steam
  • Sugar (liquid)

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