The autoclave is a common fixture in many laboratories, making it easy to overlook the hazardous nature of the apparatus. The autoclave’s job is to render contents sterile, or free of any living organisms. Autoclaving is an effective and economical process of killing microbes through the application of moist heat (saturated steam) under pressure. Heat damages the cells essential structures rendering the cell nonviable. Failure to completely sterilize materials unnecessarily raises the risk of serious health hazards.

The following documents provide helpful information on autoclave use:

Additional information regarding autoclave use can be acquired through our Autoclave Training course.


Routine Maintenance and Efficacy Testing

The best way to ensure that an autoclave is performing properly is to conduct routine maintenance. Follow the manufacturer’s recommendations for preventative maintenance and make sure all contractors are approved by the manufacturer. Users should perform the daily and weekly maintenance procedures described in the owner’s manual.

Additionally, regular testing should include monthly efficacy tests with biological (i.e. Baccilus stearothermophilus spore testing) or chemical indicators (ie.e. 3MTM ComplyTMSteriGageTM) that verify adequate temperatures and times have been reached inside the material load to kill microorganisms. Sterility test results must be recorded and retained (a log book is useful for these records). Indicators (often called spore vials or strips) can be ordered through a laboratory supply company or Shop@UW.

Although many autoclave bags or tapes are imprinted with a dye that changes color when the correct temperature is reached, a positive reading does not ensure that the innermost parts of a large load are also sterile. The problem with this type of check is that the dye is on the surface of the load. To ensure full sterilization, testing indicators should be buried in the center of a load to validate adequate steam penetration.

Examples of safe testing methods include:

  • Place the fresh spore vial or strips inside a bag that has already been through a sterilization cycle for the test. Repeat the same sterilization procedure exactly. Then remove the strips for incubation.
  • Place the fresh spore vial or strips inside of an autoclave safe screw cap tube. Tie a string around the neck of the tube. Bury the tube in the center of the load as the bag is filled. Thread the string out of the top of the bag before you  tie it with autoclave tape. After the kill cycle is completed, open the bag and pull on the string to retrieve the spore strip for incubation.

The sterilization chamber should be cleaned and drained routinely according to the manufacturer’s guidelines. In absence of manufacturer guidelines, the following procedure may be used:

  1. Wash wetted portion of the chamber thoroughly using a mild diluted detergent (e.g. calgonite).
  2. If a soft cloth or brush and detergent do not completely remove the surface film, a nylon soap pad may be used.
  3. Never use a wire brush, abrasives, or steel wool on door and chamber assembly.
  4. After washing, thoroughly rinse with clean, soft water.
  5. Dry the chamber and leave open overnight. Record the maintenance in the appropriate log.


The University has contracts with several autoclave vendors. Information regarding purchasing contracts for autoclaves and sterilizers can be found on the Purchasing Services website.

If you are looking to purchase autoclave indicators (often called spore vials or strips), please visit the Shop@UW website and peruse their storefront for vendor options.

Biosafety Resources

Phone: 608-263-2037
Fax: 608-262-6767

To request autoclave service, contact your building manager or call CARS at 608-263-3333.