Mica Shields

Factory-direct mica shields — transparent mica plates used as protective covers in front of sight glass windows in high-temperature furnaces, boilers, and combustion chambers. Mica shields protect the borosilicate or quartz sight glass from direct flame, radiant heat, and combustion deposits, significantly extending sight glass service life. Custom sizes and OEM orders welcome.

Why Use Mica Shields?

In high-temperature combustion applications, direct exposure to flame and hot gases rapidly degrades glass surfaces through thermal shock, chemical etching, and carbon deposition. A mica shield placed in front of the sight glass acts as a sacrificial protective layer — it is far cheaper to replace a mica shield than a sight glass assembly.

Key Properties

  • Material: Muscovite mica (natural) or phlogopite mica (synthetic) — specify on order
  • Max. operating temperature: Up to 600°C (muscovite); up to 900°C (phlogopite)
  • Transparency: Semi-transparent — allows visual monitoring through the shield
  • Chemical resistance: Resistant to most acids, alkalis, and combustion gases
  • Thickness: 0.1mm to 3mm — custom available
  • Size: Custom cut to match your sight glass window dimensions
  • Dielectric strength: Excellent — also suitable for electrical insulation applications

Muscovite vs. Phlogopite Mica

Property Muscovite (Natural) Phlogopite (Synthetic)
Max. temperature Up to 600°C Up to 900°C
Transparency Higher Slightly lower
Cost Lower Higher
Best for Boilers, standard furnaces High-temp kilns, combustion chambers

Typical Applications

  • Industrial boilers — flame observation port protection
  • Furnaces and kilns — sight glass protection from radiant heat
  • Combustion chambers — burner observation window shields
  • Gas turbines and incinerators — high-temperature inspection windows
  • Electrical insulation — transformer and motor applications

Compatible Products

Use with our Flange Sight Glasses and Level Gauge Glass for complete sight glass assemblies. Pair with high-temperature gaskets for leak-free installation.

Need a custom size, thickness, or mica grade? Contact us for a quote within 24 hours →