Your first-line-of-defense, for preventing surgical instrument and endoscope corrosion, is cleaning the passive oxide layer of medical instruments. The manufacturer forms a passive oxide layer on the surface, which protects them against  corrosion. 

This makes surgical instruments as corrosion resistant as possible. It is imperative that you maintain the passive oxide layer to prevent corrosion and  maintain your surgery instruments in optimal condition. If this is not done the stainless steel will be more susceptible to corrosion, pitting and stains. This will reduce the life of the surgical instruments. Initially, all stainless steel surgical instruments have the same corrosion resistance. When strength and hardness requirements are important factors for instrument function, corrosion resistance is generally lower. Manufacturers of surgery instruments and surgical instrument containers recommend the use of neutral pH Surgical Instrument Cleaners. Surgical Instrument Cleaners with a high or low pH have been shown to erode the passive layer. The most common of these cleaning concentrates utilize an alkaline detergent with an acid neutralizer. Virtually all manufacturers of surgical instruments and surgical instrument containers recommend against using these detergents and recommend using a neutral ph Surgical Instrument Cleaner. Residue deposits (stains or spots arranged in groups or along edges or in crevices) are usually the instrument being exposed to result of high chloride content. They will lead to pitting of the surgical instrument surface if not removed. Excessively hard water can contain high levels of salt sufficient to cause stains or spots that appear as rust. Boilers used to generate the steam for steam sterilizers, if not cleaned properly, will produce contaminated steam which can deposit minerals onto instruments during the sterilization process. Neutral pH Cleaning Concentrates recommended by Device Manufacturers. Do not use high acidic (pH <4) or high alkaline (pH >10) products for disinfection or cleaning, since these can corrode metal, cause  discoloration or stress fractures. 

Surgical Instrument Washers using highly concentrated, lubricating, neutral pH, detergent, four enzyme Surgical Instrument Cleaners and the ONEcleaner highly concentrated, lubricating, neutral pH, detergent, four enzyme Endoscope Cleaners prevent spotting. 

Combination Surgical Instrument Cleaners can be effective in treating unacceptably hard source water and removing hard water encrustation from surgical  instruments and equipment. Surgical Instrument Washer that use; highly concentrated, enzyme, detergent, lubricating, detergent, neutral pH Surgical Instrument Cleaners and highly concentrated, enzyme, detergent, lubricating, detergent, neutral pH Endoscope Cleaners reduce reprocessing costs and boost productivity. 

place groups of instruments in a covered container with appropriate enzyme-detergent Surgical Instrument Cleaners or apply an enzyme-detergent foam spray to delay drying. The use of pre-soaking enzyme-detergent Surgical Instrument Cleaners have been shown to reduce the time expended for manual cleaning and render higher quality outcomes. After surgery, open all box locks and disassemble instruments with removable parts. This will limit blood  drying on instruments that may cause them to corrode. 
Surgical Instrument Cleaners and lubricating, four enzyme, highly concentrated, detergent, ONEcleaner Surgical Instrument Cleaners deliver a chemical complex to: maintain the hydration of bioburden, prevent corrosion, clean the surface, and condition the surface of instruments. This can significantly reduce manual cleaning and facilitate cleaning the surface of surgical instruments. 
Surgical Instrument Cleaners and ONEcleaner lubricating, highly concentrated, combination detergent Surgical Instrument Cleaners can render excellent outcomes and facilitate cleaning instruments. This can eliminate or reduce the manual labor expended, rendering lower reprocessing costs while improving turnaround.

Surgical Instrument Cleaners and Endoscope Cleaners and that are using a properly designed (using the proper sequence of treatments) automated Surgical Instrument Washers provide proper cleaning and the prerequisite for sterilization. 

Ultrasonic Cleaners and Surgical Instrument Washers reduce reprocessing costs. 

Surgical Instrument Cleaners and Endoscope Cleaners maintain moving parts and protect instruments from staining and rusting during sterilization and storage. Most automated washer decontaminators provide the option for lubrication at the end of the final rinse treatment. Since effective ultrasonic  cleaning removes all lubricant, re-lubrication is important. ONEcleaner Surgical Instrument Cleaners will provide lubrication. The lubricant should contain a chemical preservative to prevent bacterial growth in the lubricant bath. The bath solution should be made with purified water. A lubricant containing a rust inhibitor helps prevent electrolytic corrosion of points and edges. Immediately after cleaning, instruments should be immersed or rinsed for 30 seconds and allowed to drain off, not wiped off. A lubricant film  will remain through the sterilization to protect surgery instruments during storage. Staining and spotting may result if residual chemicals are not completely rinsed from surgery instruments that are subjected to steam sterilization. Following the manufacturer’s recommendations for the proper sequence of treatments (cold water pre-wash, enzyme-detergent wash, purified water rinse/lubrication, and drying) is critical to prevent stains and spots. A Surgical Instrument Cleaner that will avoid spotting is called free-rinsing. Studies regarding the passive oxide layer of Surgical Instruments, of the stainless steel passive layer to prevent corrosion, have revealed a reduction in corrosion prevention with the use of cleaning concentrates that are not neutral pH. The use of Surgical Instrument Cleaners that deliver an acid rinse will release nickel from the stainless steel and decrease the efficacy of  the passive layer. This is most critical on initial reprocessing events of stainless steel surgical instruments. Measurable levels of nickel have been detected. It was also  shown that, as the number of subsequent uses increased, the level of nickel release diminished and reached a steady state (measured in the order of μg/l). These  observations reflect the changes that occur in the passive oxide layer on first immersion of stainless steels in aqueous media. 

What is a Stainless Steel Surgical Instrument? 
Stainless steel is essentially a low carbon steel which contains chromium at 10% or more by weight. It is this addition of chromium that gives the steel its unique stainless,  corrosion resisting properties. The chromium content of the steel allows the formation of a rough, adherent, invisible, corrosion-resisting chromium oxide film on the steel surface. If damaged mechanically or chemically, this film is self-healing, providing that oxygen, even in very small amounts, is present. The corrosion resistance and other useful properties of the steel are enhanced by increased chromium content and the addition of other elements such as molybdenum, nickel and nitrogen. Stainless steel has  a passive film created by the presence of chromium and often other alloying elements, nickel, molybdenum that resists this process. When exposed in air, stainless steels  passivate naturally due to the presence of chromium. But the time required can vary. In order to ensure that the passive layer reforms rapidly after pickling, a passivation  treatment is performed using a solution of nitric acid and water.

How is the passive oxide layer Manufactured and Maintained  when Cleaning Surgical Instruments and Cleaning Endoscopes?
The passive layer or stainless steel is intended to prevent or resist corrosion. The process is called Passivation. Passivation and Polishing eliminate the carbon molecules  form the instrument surface. This forms a layer which acts as a corrosive resistant seal. Passivation is a chemical process that removes carbon molecules from the surface  of the instrument. This chemical process can also occur through repeated exposure to oxidizing agents in chemicals, soaps, and the atmosphere. Polishing, by the manufacturer, is a process used to achieve a smooth surface on the instrument. Surgical Instruments are polished because the passivation process leaves microscopic pits where the  carbon molecules were removed. Polishing also builds a layer of chromium oxide on the surface of the surgery instrument. Proper cleaning, handling, and sterilization will build up the layer of  chromium oxide and protect the Surgical Instrument from corrosion and /or pitting. In some circumstances older instruments have higher resistance to corrosion than new ones. The newer instruments have not had the time to build up the chromium oxide layer. Improper cleaning and sterilization can cause the layer of chromium oxide to disappear or become damaged thus increasing the possibility of corrosion and/or pitting. Proper cleaning and sterilization can cause the layer of chromium oxide to improve over time thus decreasing the possibility of corrosion and/or pitting. 

John Temple
Product Development 
Surgical Instrument Cleaners  and Endoscope Cleaners 

Surgical Instrument Cleaners cleaning surgical instruments prior to sterilization
cleaning surgical instruments prior to sterilization
cleaning surgical instruments prior to sterilization