Type of Surface Change
Yellowish-brown to blue-violet discolorations of various forms, ranging from extended and rainbow-like tarnish to colored spots or droplet-shaped stains.
Origin & Causes
- Silicic acid leakage in the production of fully demineralized water when using ion exchangers and reverse-osmosis water treatment plants.
- Carry-over of cleaner residues containing silicates into the final rinse in machine-based treatment processes.
- Other mineral substances (e.g. copper) contained in the final rinse water of mechanical cleaning processes or in the steam condensate.
- Mineral deposits can be removed by acid-bases cleaning using special detergents as recommended by the manufacturer.
- Stubborn deposits (silicate build-up) can be removed with agents containing hydrofluoric acid, or through mechanical surface treatment by the manufacturer or a qualified repair service provider.
- Use silicic acid-free, fully demineralized water for final rinse in machine-based processing.
- Prevent cleaner carry-over by:
- correct tray loading and proper positioning/fixation of items with hollow spaces in which liquids can accumulate (e.g. kidney-shaped bowls).
- Ensure sufficient neutralization and intermediate rinsing in mechanical cleaning processes.
- Use water quality as specified in EN 285 (Annex B, Table B.1) or DIN 58946, Part 6, for steam sterilization.
- Ensure correct functioning of your dosing equipment.
- No corrosion, only aesthetic effect; no hygienic hazards.
- The laser-lettered labels of instruments may be adversely affected (bleached) when treating them with acid-based cleaners. This may result in poor legibility, thus impairing or even destroying their coding function.