Mica Sheild

Why Use Mica Shields?

Even the toughest gauge glass will degrade over time when exposed to steam, acids, or corrosive chemicals — often resulting in cracking, etching, or a “melted” appearance. A mica shield forms a protective barrier between the process fluid and the glass surface, effectively preventing corrosion and significantly extending the lifetime of your gauge glass.

We offer a wide range of mica shields in various sizes and grades, so you can find the right purity, durability, and clarity for your equipment and application.

Quality Grades of Mica Shields

Mica shields are visually inspected and classified into quality groups based on clarity, colour, and flatness. The appropriate grade depends on your process medium and operating environment.

• V1 Grade (Premium Quality): Clear, flat, and free from imperfections. Offers the highest level of visibility and protection. V1 mica is not obstructed by cracks, air pockets, colour variations, or other defects.
• V2 Grade (Navy-Grade Quality): Slightly coloured but maintains excellent clarity and performance. Suitable for most demanding applications.
• V4 Grade (Industrial/Economy Quality): The most cost-effective option and ideal for general-purpose use. These shields may have slight discolouration, air pockets, or a wavy appearance, but still provide reliable protection against steam and alkaline solutions, with only a minor reduction in visibility.

At John Moncrieff Ltd, we provide mica shields tailored to your exact requirements — ensuring long-lasting protection, reliable performance, and superior optical clarity in every application.

Please see below link to our Technical Information: