Autoclave Tape-Introduction, Principle, Testing Procedure, Result-Interpretation, and Keynotes
Autoclave tape before autoclaving
Introduction
Table of Contents
Autoclave tape is a commonly used chemical indicator in microbiology and clinical laboratories to monitor sterilization by steam autoclaves. It provides a visual confirmation that the materials have been exposed to specific sterilization conditions. While it does not prove sterility, it is an essential first-line check in laboratory quality control (QC).
Fig. Autoclave Tape
Principle
Autoclave tape is coated with heat- and steam-sensitive chemical dyes.
During autoclaving (121 °C, 15 psi, 15–20 minutes), the chemical indicator undergoes a color change (typically beige/white → dark brown/black).
The change occurs only when the tape is exposed to the required temperature and steam for a sufficient amount of time.
This confirms that the autoclave cycle reached sterilization parameters.
Testing Procedure
Preparation
Wrap the tape securely around glassware, media bottles, or packs to be sterilized.
Ensure it is visible after the autoclave cycle.
Autoclaving
Load materials into the autoclave chamber.
Set at 121 °C, 15 psi, 15–20 minutes (standard cycle) or other validated cycles.
Observation
After completion, remove the items carefully.
Observe the tape: a distinct color change (lines turning dark brown/black) indicates proper exposure.
Result-Interpretation
Fig. Autoclave tape before autoclaving
Positive QC (Valid Cycle): Clear, uniform color change of the indicator lines as shown in the image below.
Negative QC (Invalid Cycle): No color change, faint change, or patchy markings → suggests incomplete exposure or autoclave malfunction.
Fig. Autoclave tape after autoclaving
Keynotes
Autoclave tape is a Class 1 chemical indicator (process indicator).
It is simple, inexpensive, and quick to interpret.
Always combine with biological indicators and autoclave performance testing for complete QC.
Failure to change color suggests improper loading, poor steam penetration, or autoclave malfunction.
Should be stored in a cool, dry place to maintain accuracy.
This tape does not prove the sterility of the load. It only indicates that the conditions for sterilization were reached.