| What is Stainless Steel? | |
| Stainless steel is an alloy, which does exactly what its name implies: stains less than ordinary steel (iron). Yes, it can stain, discolor and rust, given the right circumstances. To make iron stainless, nickel and chromium are added in certain quantities, depending on the purpose it is being used for and the qualities required. The more chromium added to the mix, the softer the alloy becomes, something not desirable in a surgical instrument. Given that, quality medical stainless steel alloy is of a very specific, narrowly defined mix. A further aspect of making steel stainless is a repeated process of extracting surface impurities, mainly minerals. And the final high polish of the finished instrument puts a minute protective coating on it, also very important to make the instrument "stain less".Whether the final product is highly polished or mat finished will make no difference in its stainless ability. | |
| Austenitic | |
| This is a non-heat treatable stainless steel with low carbon content. It is corrosion-resistant and malleable, which makes it ideal for hooks, specula, calipers and retractors. | |
| Martensitic | |
A heat-treatable stainless steel, this material can be worked in a soft state and then be hardened to increase strength. It will be found most often in forceps, scissors, rongeurs, curettes, trephines, knives and needle holders. Stainless steel resists rust and can be finely sharpened. Its name, however, is somewhat misleading, for stainless steel can spot, stain and pit or corrode if not properly cared for. Other materials can also be utilized in the manufacture of surgical instruments, including silver, titanium and other alloys. Each has properties and characteristics that require vigilance in care and handling. Proper care, cleaning, handling, inspection and sterilization are the key to proper instrument performance and extended usefulness. |
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| How should I clean my instruments? | |
| This depends on how sterile your protocol requires them to be. First rinse in pH neutral distilled water and remove blood and debris. Use a fresh neutral pH solvent and then a soft brush for the tough cleaning. If you steam autoclave, make sure that you use manufacturer's instructions for your autoclave (clean neutral pH distilled water), and that your high quality instruments are not mixed with instruments of inferior quality. Impurities from the lower quality instrument can start a corrosive action on your good ones. Be sure that the full drying cycle is used. Overlapping joints may have dampness within the joint, increasing the chance of corrosion. This can be prevented in three ways: assure the full drying cycle is complete, apply silicone grease inside the joint as a protective layer, or by use of an air canister or hair dryer to blow moisture out of overlapping parts. Instruments can also be cleaned ultrasonically but must be immediately rinsed and dried. It has been our experience that the longest lasting instruments are typically the ones soaked in 70% ethanol before and after use, then rinsed and dried. | |
| I bought two of the same instruments and they are different! | |
| High quality surgical instruments are handmade which can lead to some minor variations in the dimensions of instruments, particularly between manufacturing sets. This is sometimes noticeable in the finest spring scissors and the tips in Dumont forceps. | |
| My instruments are rusting. What should I do? | |
| Proper cleaning of your instruments right after use is the first step to prevent rusting. In most cases, what is perceived as rust is really dried blood, which, if left on the instrument will start corrosive action. Soak instruments right after use in a dish of pH neutral distilled water or a solution of neutral pH detergent. A soft toothbrush will help remove the softened materials. Soak up to an hour and never re-use solution. Rinse in distilled clean water and dry with clean lint free cloth. Be sure overlapping surfaces are completely dry; a hairdryer will help here. Ultrasonic cleaners can also be used, but be sure to follow manufacturers instruction fully, particularly in the concentration of the solution to be used. Instruments can also be steam sterilized; but follow manufacturers instructions. Use only distilled water; be sure to run the drying cycle to its end, so that instruments are completely dry; never mix good quality instruments with those of inferior quality, as impurities from the poor quality instruments could settle on your good ones and start a corrosive action. | |
| How can I prevent my stainless steel instruments from staining? | |
| 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 chlorite 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. 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. I work in salt water. |
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When I should ask for titanium instrument? |
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If you must use your surgical instrument in a corrosive environment, or you need a completely non-magnetic instrument, or it has to tolerate heat of up to 440 C or 824 F, an instrument made from titanium alloy can be your answer. Other benefits are: 40% lighter than stainless steel; better strength to weight ratio than stainless steel; better flexibility than stainless steel; it exhibits bactericidal and non-allergenic properties. Artery clamps made of titanium alloy (90% Titanium, 6% Aluminum, 4% Vanadium), are now being used in MRI's with acceptable results. Consider that it will wear down faster than stainless steel. |
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| What does the gold handle mean? | |
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A gold handle on scissors, forceps, or needle holders means they have tungsten carbide (TC) inserts on the working surfaces. TC is one of the hardest alloys used for surgical instruments. They are approximately twice as expensive as standard instruments, but can last five times longer, cutting the same tissue. This can be very cost effective in the long run Origin & Causes The corrosion resistance of stainless steel primarily depends on the quality and thickness of the passive layer. This is a protective layer of iron/chromium oxide that results from the chemical reaction between the chromium in the steel alloy (at least 12%) and oxygen in the ambient air. This layer is not affected by the specific surface finish of the product (matte or high-gloss). In fact its formation and growth are influenced by the following factors:
Pitting and stress corrosion cracking are seldom or never observed in a chloride-free or low-chloride environment. This is irrespective of the degree of gloss and the given passive layer of the instrument surface. If corrosion only occurs on new instruments processed in the same cycle with older instruments, the reason can probably be found in the instrument processing conditions. |
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