What to Do When a Chemical Indicator Does Not Change Colour
What should you do first when a chemical indicator does not change colour?
Hold the load. Do not release it to storage or to a patient while an indicator that should have changed has not; a check that did not confirm the conditions is a signal to stop and look. A Class 5 steam chemical integrator or a strip of autoclave indicator tape is meant to make a fault visible, so a quiet indicator has done its job.
Which chemical indicator are you reading?
Name the indicator first. Chemical indicators are grouped into classes under ISO 11140-1, and each class confirms something different. Treating a Class 1 tape as proof of conditions inside a pack is itself a common source of confusion.
| Class | What it monitors | Where it sits |
|---|---|---|
| Class 1 | Process indicator - exposure to the process | Outside the pack, as tape or a label |
| Class 2 | Specific test, such as a Bowie-Dick test | In an otherwise empty chamber |
| Class 3 | A single critical variable | Inside the pack |
| Class 4 | Two or more critical variables | Inside the pack |
| Class 5 | All critical variables, integrating | Inside the pack, read to an endpoint |
| Class 6 | Emulating indicator, cycle-specific | Inside the pack, matched to the cycle |
What are the common reasons it did not change?
Start with the obvious and work inward. A Class 3 or 5 internal indicator that never reacted usually means it did not see the conditions, not that the cycle was set wrong. The usual causes are the wrong class for the cycle; an indicator placed where air and steam cannot reach it; an expired or badly stored indicator; an overloaded chamber; and a cycle that did not reach its parameters. Heat damage in storage can desensitise an indicator before it is ever used.
What is the step-by-step response?
1. Hold the load and mark it unreleased.
2. Identify the indicator class and where it was placed.
3. Check the expiry and how the indicators have been stored.
4. Inspect the pack and loading pattern for air and steam access.
5. Confirm the cycle selected matches the load.
6. Repackage with a fresh indicator, matched to the cycle, using a Class 4 dual-indicator sterilization pouch, and reprocess.
7. If a second cycle shows the same result, stop and have the sterilizer checked.
Document each step - the record shows an inspector that the failed indicator was investigated.
Can a load be released on the biological indicator alone?
A passing biological indicator is the strongest routine evidence that a load is sterile, and in Ontario a biological indicator is required for each sterilizer on every day it is used. But a chemical indicator that failed to change still points to a fault, and those faults recur. Treat the two readings as complements, not substitutes.
When should the sterilizer be checked by a service provider?
If a fresh, correctly placed indicator fails again after a re-run, the fault is likely mechanical: an air-removal or steam-quality problem, a drain or vacuum fault, or a door seal that is passing. That is a service call, not another re-run. Keep the failed indicators and the cycle records with the service log.
Working in a dental practice? See our dental practice sterilization and monitoring supplies for the indicator classes and biological monitoring lines kept for chairside reprocessing.
Ordering for a clinic, lab or care home? Wholesale and multi-site ordering covers case pricing and account setup, and the B2B wholesale collection lists the lines stocked for institutional buyers. Reselling? become a distributor.
References
- ISO 11140-1 - Chemical indicators for sterilization (via Genorma) (checked 4 October 2026)
- Public Health Ontario - Cleaning, disinfection and sterilization in health care settings (checked 4 October 2026)
Printable companion: the free sterilization log sheet lays out the fields an inspection asks for, so a failed indicator is written down as it happens.
The sterilization log generator then prints a record with the columns your reprocessing documentation needs.
Not sure how this applies to your own setup? Ask a sterilization compliance specialist — you’ll get a written answer specific to your equipment and province, with the regulation or standard cited.
Where to Buy Biological Indicators in Canada
CliniEco Medical supplies these from Ontario with published CAD pricing (MDEL #35334) — no quote required, and each pack ships with the lot number printed on it so your monitoring record stays traceable.
| Format | Pack size | Price (CAD) | |
|---|---|---|---|
| 24-hour self-contained | 25-pack | $84.99 | Order |
| 24-hour self-contained | 100-pack | $299.00 | Order |
| 3-hour rapid fluorescence | 50-pack | $274.99 | Order |
Round Out Your Sterilization Setup
A biological indicator is one link in the chain — these are the pieces it works with:
- Sterilization roll — 50 m pre-cut sheets for larger instruments
- Constant-heat pouch sealer — 200 °C, 12 mm seal — for consistent pouch closures
Which format does your sterilizer actually need?
Match the readout time to how fast you need the result: a 24-hour self-contained indicator works in any gravity or pre-vacuum cycle with a standard incubator, while a 3-hour fluorescence tube needs the matching reader. Running one cycle type per day, the 25-pack covers a month; busier clinics move to the 100-pack and cut the per-test cost.
How much do spore tests cost in Canada?
Published pricing runs $3.40 per test on the 25-pack down to $2.99 on the 100-pack — no distributor quote, no account needed.
Not sure which format your sterilizer needs? Generate a free sterilization log sheet first — it maps your cycles and tells you the pack size that fits. Questions about your setup? Ask a Compliance Specialist.
Related Reading
- After an Autoclave Cycle, How Do You Read the Tape and Pouch Indicators?
- Internal and External Chemical Indicators: Where Each Goes on the Pack
- Why Does Autoclave Tape Change Colour but the Internal Indicator Stay Pale?
Frequently Asked Questions
What should you do first when a chemical indicator does not change colour?
Do not release the load. Hold it, confirm which indicator was read and where it sat, and work through the causes before the items go back into circulation.
What is the difference between a chemical indicator and a biological indicator?
A chemical indicator reacts to one or more conditions of the process and shows they were reached. A biological indicator uses live spores and is the only routine monitor that gives assurance of sterilization.
Can a load be released on the biological indicator alone?
A passing biological indicator is the strongest routine evidence, but a chemical indicator that did not change still points to a process or handling fault. Investigate it and document it rather than treating the two readings as substitutes.
Last updated: October 2026. CliniEco Medical is a licensed medical device establishment (MDEL #35334).
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