A. Tungsten carbide (TC) inserts are much "harder" than regular stainless steel and therefore retain their sharpened edges longer than stainless steel. However TC inserts require special care and handling during processing.
If an ultrasonic cleaner is utilized, please follow manufacturer’s instructions regarding solution dilution and the length of time the instruments are left in the solution. Please use only solutions that contain a corrosion inhibitor.
If a steam autoclave is utilized, please be sure to use a corrosion inhibitor – surgical milk “Cleanlact” and many products exist in the market- place for this purpose. Please be sure that tungsten carbide instruments dry quickly during the “dry” or “vent” cycle of the autoclave – if the instruments are not drying or are removed wet, corrosion is still possible.
Q. Should hinged instruments be sterilized in the opened or closed position?
A. Sterilization can be achieved only if the sterilizing agent (e.g., steam) contacts all instrument surfaces. Therefore, hinged instruments, such as hemostats, scissors, and extraction forceps, should be sterilized in the open position to ensure that the sterilizing agent adequately contacts all surfaces.
Q. What is staining?
A. Staining is a surface deposit on instruments, and most often mistaken for rust. After autoclaving, you may notice a stain on your instruments. Rusting instruments are very rare. Stains on instruments appear in many colors and, in most cases, the colours tell you about the origin of the stain.
Q. What are the different types of staining and what do they indicate?
A. Following are different types of staining and their indications
The problem is most often a phosphate layer (brown to light orange) on the instrument, which develops as a result of any of the following causes: water sources, detergents used to wash and clean instruments, surgical wrappings, cold sterilization solutions, or dried blood.
The most common black stains are due to an acid reaction. Black stains may result from detergents used to clean the instrument; similar to brown stains caused by high pH in detergents. The black acid type stain can be caused by low pH (less than six) during autoclaving.
Dark Brown Stains
Dark brown stains are usually a result of dried blood left on an instrument. Blood should be removed from the surface of the instrument immediately. It will break down the instruments surface with a chemical reaction.
These are usually a result of plating and are extremely difficult to remove from the surface. The surface beneath the stain is always smooth, but the instrument may have to be refinished by Surtex to obtain good results. The cause for this stain is the mixing of dissimilar metals in ultrasonic cleaners and during autoclaving. Multi-color stains are most often due to excessive heat (chromium oxide stains), and actually show rainbow colors with a blue or brown overtone. When the instrument shows these heat stains, it may have lost part of its original hardness, and may not perform well. These instruments can usually be refinished, and the hardness tested. The staining can be polished off.
May result from contact with ammonia. Many cleaning compounds contain ammonia, which remains on the Instrument if not rinsed thoroughly. Can also result from amine deposits traced in the autoclave or steam pipes. Follow autoclave cleaning with a cycle of distilled water.
Rusting instruments are very rare. What appears as rust is actually residual organic matters or mineral deposits in box locks, ratchets, serrations, hinges etc. which have been baked on to the surface.
Sterilization of stainless instruments together with plated instruments of dissimilar material should be avoided. Chipped or imperfectly plated carbon steel instruments will cause rust deposits on stainless steel instruments. Electrolytic action will carry carbon particles from the exposed metal on to the stainless steel surface. These particles promptly oxidize and the stainless steel instrument appears to have rusted.
A rust-color film on instruments can be caused by the high mineral content or by the use of water softeners.
Q. What recommendations does Surtex Instruments give to prevent instruments from staining?
A. Never remove the final polishing film by rubbing or sanding. Never leave it in tap water for any length of time. Acidic or alkaline pH will remove chromium oxide and chloride ions will cause pitting. Copper, iron and manganese will cause brown and blue rainbow effects. Distilled water with a neutral ph can be used sparingly.
To minimize staining, it is important that the autoclave runs perfectly, and that it has a well-functioning drying cycle. The instruments should come out completely dry, whether in wrappers or loose on a tray. If any moisture is left in the pack, or on the instruments, it will result in tiny water droplets on the instrument surface, which will leave a circular stain after drying. The color of this stain will depend on the pH, as well as the mineral or metal contents of the water. If the drying cycle works perfectly, however, there is a much less chance for deposits to form on the surface of the instrument.
Stains due to metal deposits or plating stains are always near the most magnetic parts of the instrument. New instruments are often highly magnetic in the locks, the serrations and ratchets. This happens because the carbon steel tools used to work on the instruments during production are very magnetic themselves. This magnetism wears off gradually during handling and sterilization. This is the reason why newer instruments tend to stain more visibly. Rubbing the instrument with Surgical Instrument Oil, (also called Instrument Milk) and putting a drop of it between overlapping surfaces, will aid in keeping your surgical instrument for years to come.
Q. How does corrosion and pitting occur and how to prevent it?
A. Following are reasons for corrosion and pitting:
Presence of blood and soil in box locks, ratchets, serrations, hinges etc. can cause corrosion. More care should be taken in cleaning. Excessive moisture left on the surface of the instrument can lead to corrosion. Preheat the autoclave, do not rush the drying time.
Foreign matters deposited in the autoclave can result in spotting and corrosion of instruments. Inner surfaces of the autoclave should be given a routine maintenance. Wipe down with acetic acid (equal parts of vinegar and distilled water) to remove any impurities. Stress corrosion can be caused by not opening box locks during sterilization procedure. The heating-up and cooling-down process during sterilization causes tension in the material.
When instruments are exposed to saline solutions, blood, iodine, potassium chloride and other compounds pitting will occur. Instruments should be rinsed thoroughly immediately after exposure. Pitting can also be traced to detergents with a high pH level (B-9) used for instrument cleaning. Instruments should be thoroughly rinsed after cleaning. It is impossible to completely restore an instrument after pitting or rust has eroded the hard surface. The instrument should be replaced immediately as a pitted instrument is far more susceptible to further corrosion.
Q. Why is it important to use correct water quality during reprocessing?
A. The quality of water used during reprocessing is critical for the proper care and handling of instruments.
Water fulfills a number of functions during the reprocessing cycle.
- Dissolves cleaners and other treatment agents.
- Transmission of mechanical forces and transfer of heat to surface of the items to be washed.
- Dissolve soluble dirt and impurities.
- Flushes away cleaning and treatment solutions.
Unfavorable water composition can have adverse effect both on the treatment process and the appearance of instruments and materials. This is why water quality is critical during reprocessing cycles.
All natural water contains dissolved salts, concentrations very depending on the source of the water and purification processes used.
Depending on water hardness and temperature, fresh water used can lead to formation of hard layer (lime deposits, scale) that is difficult to dissolve. It is even possible for corrosion to occur underneath such deposits.
In softened water, alkalinity can greatly increase as a function of temperature and exposure. Especially when thermal disinfection is used in the final rinse, aluminium surfaces might be subject to attack.
When water evaporates, some substances contained in it remain as visible mineral residues. Chlorides dissolved in water are particularly critical substances because they tend to cause pitting even on stain-less steel instruments if present in higher concentrations.
To prevent excessive chloride concentrations and subsequent pitting we recommend using only fully demineralized water for the final rinse.
Other substances may cause brownish, bluish, gray-black or iridescent discolorations even when present in small quantities. Such discolorations may be caused silicates/silicic acids contained in the water, or by compounds containing iron, copper or manganese. As a rule however, such discolorations are harmless, constituting very thin residual layers that do not cause or facilitate corrosion.
Apart from its natural constituents, drinking water sometimes contains rust, generally flushed from corroded pipework. During the processing cycle this rust tends to adhere to instruments, causing rust spots (extraneous rust) and subsequent corrosion.
The use of fully demineralized water in the final rinse is not only recommended for the reasons described above (i.e. preventing chloride de-induced corrosion) but also because it helps keep the surfaces of the instruments free from stains and discolorations, and stabilizes anodized aluminium surfaces.
Q. Which is the best method for cleaning instruments, manual (e.g, scrubbing instruments with a brush) or automated?
A. Debris can be removed from an instrument either by scrubbing the instrument manually with a surfactant or detergent and water or by using automated equipment (e.g., ultrasonic cleaner, washer-disinfector) and chemical agents. After cleaning, instruments should be rinsed with water to remove chemical or detergent residue. Splashing should be minimized during rinsing and cleaning. Considerations in selecting cleaning methods and equipment include their effectiveness, their compatibility with the items to be cleaned, and the occupational health and exposure risks they pose. Because instruments cleaned with automated cleaning equipment do not need to be presoaked or scrubbed, the use of automated equipment can increase productivity, improve cleaning effectiveness, and decrease worker exposure to blood and body fluids. Thus, using automated equipment can be more efficient and safer than manually cleaning contaminated instruments.
Q. How do I perform manual cleaning?
A. If manual cleaning is not performed immediately, instruments should be placed into a container and soaked with a detergent, a disinfectant/detergent, or an enzymatic cleaner to prevent drying of patient material and make manual cleaning easier and less time consuming. Surtex also recommends using long-handled brushes to keep the hand as far away as possible from sharp instruments.
Q. What type of personal protective equipment is necessary when cleaning instruments and surfaces?
A. Instruments should be handled as though contaminated until processed through the sterilization cycle (unless the instrument has been processed with a thermal washer/disinfector that has a high-level disinfection cycle). To avoid injury from sharp instruments, personnel should wear puncture-resistant, heavy-duty utility gloves when handling or manually cleaning contaminated instruments and devices. Because splashing is likely to occur, they should also wear a facemask, eye protection or face shield, and gown or jacket. Employees should not reach into trays or containers holding sharp instruments that cannot be seen. To reduce their risk of injury, they should instead remove instruments using forceps or empty them onto a towel.