User guide for chemical indicators for moist heat sterilization (autoclaves)


The autoclave must be checked daily using chemical indicators. The chemical indicators show if the physical parameters of time, temperature, and presence of dry saturated water vapor, are met during the sterilization process.

The test must be performed on all autoclave programs used in the clinic.

The indicator can be cut into two pieces. There is an instruction on the box, and a line on the indicator itself.


The chemical indicators are placed where it is most difficult for the steam to penetrate in the autoclave. The chemical indicators are used alongside equipment and can be placed in autoclave bags and cassettes (if used), so the placement is as close to everyday use as possible. The autoclave is packed and run as usual.

Sterilization time by the most used heat/time combinations

Steam sterilization:

  • 121°C for a minimum of 15 min.
  • 134°C for a minimum of 3 min.

After sterilization

The indicators should be checked immediately after emptying the autoclave.

Check if that the chemical indicators are the same colour, or darker, than the reference field on the indicator, and if the colour change is homogeneous across the indicator.

If the indicator has not changed colour from white to black after sterilization, repeat the sterilization process with a new indicator.

If the same result reoccurs, the autoclave should be inspected, and corrective action taken to remedy the problem according to the clinic's procedure.

We recommend storing the used chemical indicators for a minimum of 3 months as documentation for daily testing. Note the date of the test and signature on the back of the test.

Fill in results in a logbook as per internal standards.