What are Air Filters Made of? A Comprehensive Guide

Air filters are essential components of any heating and cooling system, as they help to clean the air circulating in the system. The most common type of air filter is made of spun glass fiber material or pleated paper or cloth enclosed in a cardboard frame. Cotton-based air filters, foam air filters, and metal filters are also available, each with their own advantages and disadvantages. Ultra-Low Particulate Air (ULPA) filters are the most effective at cleaning the air, but they are not practical for most HVAC systems due to their thickness.

Oven air filters protect oven mechanisms from getting dirty and also remove particles from the air you breathe. When choosing an air filter for your home, consider factors such as whether there are pets in the house, if mold or mildew is a threat, and how often filters should be changed. The basic function of an air filter is to clean the air circulating in the heating and cooling system. The “paper” used is a compacted wood pulp that is joined together to make a much stronger material, which is then folded into an accordion shape to give more surface area and is joined to a rectangle of foam.


parts feature layers of cotton gauze sandwiched between an aluminum mesh, which provides a less dense material for air to penetrate than paper.

This should theoretically be less restrictive, allow more air to enter and increase power. However, any bump in the start is likely to be small; a possible change in induction noise will be the only noticeable change in the driving experience. Cotton air filters can last the life of the car, although they need to be cleaned and re-greased once they are sufficiently dirty. You should ensure that you do not over-lubricate the filter, as this can cause oil to enter the mass flow sensor.


air filters use multiple layers of foam with different densities to stop contaminants, plus a wire mesh to help maintain the filter's shape.

The downside is that there are fewer restrictions, which means it won't be as effective a filter, but under most conditions, this is unlikely to cause a problem for your engine. Many use an oil application to trap incoming dirt. Also like cotton filters, it's possible to purchase one as a flat “panel filter” that fits inside your existing airbox.


filters are made of stainless steel mesh layers and do not need to be greased. In addition, with larger gaps between filter material, a metal filter will be less restrictive than cotton and foam designs.

However, once again, with fewer restrictions comes less filtration. This design will naturally let more dirt through, although the particles are not likely to be large enough to cause problems.

Ultra-Low Particulate Air (ULPA)

Filters can remove even smaller particles in the air, up to 0.12 microns in diameter with a minimum efficiency of 99.99%. In the past, foam was widely used in air purifiers in small engines, lawn mowers, and other power equipment, but automotive-type paper filter elements have largely supplanted oil-moistened foam in these applications. The indoor air quality (IAQ) of your home depends in part on the type of filters in your oven. Foam air filters are made of designed porous foams made of polyurethane, polyether, polyester, or a combination of those materials.

Cotton filters have higher ratings and their fibers can self-charge to remove the smallest particles from the air. Used as a pre-filter in multi-stage air filtration systems to prevent large particles from reaching the main filter. In general, high-efficiency filters that are also cost-effective are best for homes. Engine air filters must be replaced between 15,000 and 30,000 miles depending on vehicle type and driving conditions.

Janice Kampman
Janice Kampman

Subtly charming musicaholic. Zombie evangelist. Incurable travel lover. Devoted beer enthusiast. Passionate zombie specialist.

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