Micro-glass fibre

In attempting to eliminate small particles, thin fibres need to be used in the filter materials. Glass fibre has proven to have suitable filtering characteristics. The typical fibre diameter in the various filtering classes is approximately as follows:

• F5 (EU5) 4.0 μm
• F6 (EU6) 2.6 μm 
• F7 (EU7) 1.2 μm 
• F8 (EU8) 1.0 μm

Also, thicker glass fibre mats are manufactured for coarse mesh filter use, in which the fibre diameter is approximately 25–30 μm.

Synthetic, plastic fibres

The benefit of plastic polymer fibres is that the materials are durable. The plastic fibres can be electrically charged to improve the small particle separation level. The quality of the dust that burdens the filter fundamentally affects the sustainability of the electric charge. As a fibre filter is burdened, its mechanical separation mechanisms improve while its electrical separation mechanisms may weaken. Both the charged and non-charged separation level should be stated for electrically charged fibre filters.

Other materials

The paper-like filter material used in compact filters may be made of glass fibre, synthetic materials, or natural cellulose. The fibre sizes and their combinations vary with the desired separation level and pressure loss. The materials may be saturated to withstand humidity.  Stable, thin filter mats also use cotton/polyester compounds and a metal grid to support the filter material.