Methods of Sterilization I: Physical Methods

Sterilization procedures use various physical and chemical methods.

Commonly used physical methods are steam, dry heat, boiling water, and radiation.

In steam sterilization or autoclaving, the objects come in direct contact with non-toxic, dry saturated steam at the recommended temperature and pressure for the prescribed time.

This process is microbicidal and sporicidal and quickly warms and infiltrates fabrics.

For example, surgical instruments and linens are sterilized using steam.

Dry heat sterilization uses moisture-free heat to kill microorganisms from moisture-sensitive materials. It is non-toxic, and metal instruments are typically sterilized using dry heat because it is not corrosive.

Next, boiling water is an easy and affordable method typically used in the home for tools such as scissors and tweezers.

However, it does not eliminate spores or some viruses.

Non-ionizing radiation in the form of ultraviolet rays is usually only used for the surface sterilization of aseptic work areas.

Ionizing radiation, like gamma rays or X-rays, is a very effective but expensive sterilization method. It can be used on temperature-sensitive materials,  such as pharmaceuticals.