Instrument Stain Identification and Treatment

Contrary to popular belief the majority of instrument staining problems are not caused by faults within the instruments or the metal used within the manufacturing process. In fact over 95% of instrument staining is caused by incorrect or inadequate cleaning and sterilising processes.

The table below has been compiled in order to assist those involved in the instrument cleaning and sterilisation process identify the cause of instrument staining and recommended methods to eliminate future staining occurring.

 

Stain

Cause

Treatment

Orange-Brown to Reddish

(resembles rust)

 

If stain rubs off and no pitting exists, problem is most likely to be from:

  1. Detergent residue on towels or a high alkaline pH (>8) detergent is being used leaving a phosphate surface deposit.
  2. Dried blood.
  3. Iodine or Betadine.
  1. Check pH level of detergent and change to neutral pH detergent.
  2. Check pH of towels to verify if detergent residues are present.
  3. Rinse instruments thoroughly in warm water for a minimum of 30 seconds.
  4. Use a stain remover on both instruments and autoclave.
  5. If problem persists, consider changing to distilled water for rinsing process particularly if local water supply is high in iron or other minerals.

 

Black, Brown & Pitting

 

Subjected to a low Acidic pH (<6) substance, such as:

  1. Low pH detergent residue on instruments or towels
  2. Exposed to other chemicals compounds from “cold soaking”
  3. Exposure to Bleach or other ammonia compounds

 

  1. Check pH level of detergent and change to neutral pH detergent.
  2. Check pH of towels to verify if detergent residues are present.
  3. Eliminate exposure to chemicals or bleach.
  4. Rinse thoroughly and consider distilled water for continued rinsing. Particularly if local water supply is high in iron or other minerals.
  5. Use a stain remover on both instruments and autoclave.
  6. If pitting remains, return instrument to manufacturer for evaluation

 

Rainbow or Multi-colour

 

Instruments have been heat compromised, tensile strength is compromised

 

Check autoclave for proper temperature.

 

Bluish-Green

Bluish-Black

 

Cross-contamination between dissimilar metals

 

Separate instruments by metal type before cleaning or autoclaving.

 

Bluish-Gray

(possible pitting)

 

Incorrect preparation of cold sterilisation solutions

 

  1. Follow solution manufacturer’s direction closely, particularly temperature and soak time.
  2. Use distilled water.
  3. Change solution as per manufacturer’s instruction.

 

Rust

 

  1. Sterilising instruments of dissimilar metals in same cycle.
  2. Chemicals in detergents or excess amounts of iron or other minerals from local water supply.
  3. New instruments may be slightly magnetised during the manufacturing process.

 

  1. Separate instruments by metal type prior to sterilisation.
  2. Use neutral pH detergents and change to distilled water. Particularly if local water supply is high in iron or other minerals.
  3. Wipe off residue leaving shiny metal underneath.
  4. Use stain remover on both instruments and autoclave.
  5. After several autoclaving treatments, the new instruments will lose their magnetic property.

 

Spotting Light or Dark

 

Slow evaporation of water drops with mineral content

Instrument wraps and towels may contain detergent residue

 

  1. Eliminate water droplets and moisture by adhering to autoclave operating instructions.
  2. Use stain remover on both the instruments and autoclave.
  3. Use neutral pH detergents and change to distilled water. Particularly if local water supply is high in iron or other minerals.
  4. 4. Wash wraps and towels in neutral pH detergent.

 

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