FAQ

Price is driven by three core factors: raw-material grade (the fewer the impurities, the more expensive), heat-resistance class (the higher the temperature rating, the more expensive) and machining precision.

Muscovite is silvery-white or transparent. It has better electrical insulation performance but a relatively lower temperature rating (around 600°C), and is well suited to high-voltage electrical insulation.

Phlogopite is golden or amber in colour. It performs better at high temperature (around 850°C) but is slightly lower in insulation performance than muscovite, and suits high-temperature heating equipment.

It depends on the type of mica:

• Muscovite — continuous service to about 500–600°C, short-term up to 800°C.
• Phlogopite — continuous service to about 700–850°C, short-term up to 1000°C.
• Synthetic mica — can exceed 1000°C.

It depends on the application. Synthetic mica is purer, contains no impurities and withstands higher temperatures (above 1000°C), which makes it suitable for high-end optical or extreme high-temperature environments. Natural mica offers better value for money and suits the vast majority of industrial insulation requirements.

Industry-standard tolerances are typically between ±0.05 mm and ±0.1 mm. Because mica is built up by stacking and pressing layers, micron-level precision comparable to metal machining is not achievable.

Typically above 20 kV/mm. This means a 1 mm thick mica sheet can withstand at least 20,000 volts without breakdown, which makes mica an excellent high-voltage insulating material.

The raw material is natural mica ore (mainly a silicate mineral), processed by splitting, coating and lamination. Genuine mica products contain absolutely no asbestos. Mica is an environmentally friendly mineral, non-toxic and odourless, and complies with international environmental standards such as RoHS and REACH — it is entirely different from carcinogenic asbestos.

Mica tape is mainly used for fire-resistant cables and for coil insulation in large motors. In a fire, ordinary plastic insulation melts, whereas mica tape keeps its structural integrity inside the flame so that the circuit can continue to conduct for a period of time.

Rigid board contains less binder, has higher strength and does not deform easily; it is mainly used for structural supports or spacers. Flexible sheet contains more binder, or uses a special flexible resin, and can be bent at room temperature; it is mainly used to wrap cylindrical bodies, such as the barrel of a hair dryer or motor slot insulation.

A mica tube is not drilled from a solid block. It is wound from mica paper and adhesive on a heated roller and then baked and cured. As a result, its radial dielectric strength is extremely high.

It is an assembly that uses mica sheet as an insulating support, with resistance wire (heating wire) wound around it. It is commonly found in hair dryers, fan heaters and toasters.

Transparent mica sheet is mainly used for viewing windows (such as boiler sight glasses), making use of its combination of high-temperature resistance and light transmission. Standard mica sheet is usually opaque and is used only for insulation and thermal barriers.

Yes. The mica sheet in a microwave oven prevents food spatter from reaching the magnetron antenna and helps guide microwaves. If it is scorched or perforated, the magnetron may arc or even be damaged. Replace it with a purpose-made microwave oven mica sheet.

Mica sheet is used as a thermal-runaway barrier in EV battery packs. If a single cell catches fire, the mica sheet blocks the high-temperature jet flame from reaching adjacent cells or the passenger compartment, buying valuable time for occupants to escape.

The former Chinese standard divided fire resistance into Class A and Class B:

• Class B fire-resistant cable — must withstand burning for at least 90 minutes at 750–800°C under rated voltage without breakdown (i.e. a 3 A fuse does not blow).
• Class A fire-resistant cable — must withstand burning for at least 90 minutes at 950–1000°C under rated voltage without breakdown (i.e. a 3 A fuse does not blow).

Although the classification has been withdrawn from the national standard, it is still used on key projects. Class B therefore uses phlogopite tape, and Class A uses synthetic mica tape. Test conditions are commonly specified by reference to BS 6387.

Selection can be based on the design standard and unit price. In each family the three-in-one tape is the lowest-cost main choice, followed by single-sided and then double-sided tape.

Phlogopite (golden) mica tape

• Three-in-one — a lower price than the other formats, with good insulation performance; the main choice.
• Single-sided — economical in use, but a higher price and slower wrapping; chosen less often.
• Double-sided — more consistent quality, but the highest price; chosen less often.

Synthetic mica tape

• Three-in-one — a lower price than the other synthetic formats, with good insulation performance; the main choice.
• Single-sided — higher price and slower wrapping; chosen less often.
• Double-sided — a product with more consistent quality, but the highest price; chosen less often.

Calcined muscovite tape

• Three-in-one — a lower price than the other calcined formats, with good insulation performance; the main choice.
• Single-sided — higher price and slower wrapping; chosen less often.
• Double-sided — a product with more consistent quality, but the highest price; chosen less often.

Mica tape is wrapped around the copper conductor, and the tape format depends on the taping machine:

• Single-head taping machine — use single-pad mica tape.
• Tower (multi-head) taping machine — use tower-pad mica tape.

Store mica products indoors in a dry, ventilated area away from direct sunlight. A storage temperature of around 25°C with humidity kept below 60% is recommended.

Mica is chemically inert to most acids (with the exception of hydrofluoric acid), alkalis, oils and solvents, and reacts very little. It is therefore also widely used for insulation in chemical environments.

Natural mica itself does not absorb water, but mica products are built up from a layered structure. Although the material does not dissolve in water, prolonged immersion may allow moisture to penetrate between layers, reducing insulation performance or causing delamination. Use in a dry environment is recommended.

On first heating, residual silicone resin binder in the sheet may volatilise and produce a small amount of smoke and odour. This is usually normal and disappears within a few minutes. If smoking continues, the temperature may have exceeded the material's limit.

Yes, but it takes some skill. Thin mica sheet (0.5 mm) can be cut with scissors or a utility knife. Thicker board requires a band saw, a laser cutter or a CNC machine. Note that mica tends to delaminate and fray, so use a sharp blade and control the feed rate.

In solid form (mica sheet, mica tape), mica products are harmless in normal use and chemically stable. During cutting, however, a large amount of dust is generated; long-term inhalation may burden the lungs, so a dust mask must be worn and the area kept ventilated during machining.