Knives, Scissors & Scalpels

Scalpels are small and extremely sharp bladed instruments for single-use or re-usable with replaceable blades. Disposable scalpels usually have a plastic handle with an extensible blade and are available sterile and non-sterile. Double-edged scalpels are referred to as lancets. Scalpel blades are commonly made of tempered steel, stainless steel, titanium or ceramic.

Instruments for laboratories made of various materials

Different materials offer specific advantages. Choose your tools and the materials used according to your specific needs. Chrome steel e.g. is magnetic and stainless. 18/10 stainless steel is antimagnetic and may be electrolytical polished. Advantages of steel are strength, corrosion behaviour, mouldability and welding capability. Some of our scissors, scalpels etc. are made of wironit. Wironit belongs to the group of austenitic chromium-nickel steel with 18% chromium and 10-12% nickel. At Analytics-Shop.com you find a wider variety of wironit instruments by Hammacher. Instruments made of wironit are

• absolute rust resistant,
• antimagnetic,
• resistant to acids and disinfectants occurring in the practice,
• to a large extent break-resistant,
• corrosion-resistant,
• suitable for all types of sterilization and temperatures up to 300°C without losing any of their virtues.

Further advantages of wironit are maximum elasticity and resistance, soft suspension, smooth surfaces and a long lifetime. Unlike instruments with surface protection (i.e. nickel or chromium plated), wironit instruments to not show flaking of the nickel or chromium plating, unpleasant and unhygienic appearance etc.

In the following we provide information on the specific characteristics of different materials:

• Stainless steel: Non-corroding steels that contain at least 10.5% chromium are referred to as stainless steel. It has a significantly higher corrosion resistance than unalloyed steel. Higher chromium contents and further alloy constituents, such as nickel, molybdenum, titanium or niobium, increase the corrosion resistance even more. There is three main types of stainless steel:
- Chromium steels (magnetic, non-corroding) with a chromium content of 13-18%
- Chromium-nickel steel (not/slightly magnetic, V2A-18/10 steel): V2A steel is frequently used in the lab and contains 18% chromium and 8-12% nickel.
- Chromium-nickel-molybdenum steel (not magnetic, V4A steel): V4A steel contains 18% chromium, 12% nickel and 2% molybdenum.
By further additions of molybdenum, titanium or tantalum/niobium, both of these groups can be adjusted to special requirements. A large number of instruments consist of 13% chromium steel. However this steel is only stainless in a polished state, but not resistant to acids, sublimates or all disinfection liquids. When maintained and cleaned properly, stainless steel has a very long lifetime. For cleaning stainless steel, wire brushes, plastic sponges, a stainless steel spray or scouring powder are recommended. Stand materials, containers, lab jacks, furniture, stirrers, tools, etc. are commonly made of stainless steel.

• Steel: Metallic alloys that consists mostly of iron and has carbon contents between 0.011% and 2.06% is referred to as steel. More than 2,300 steel types are listed in the register of European steels. Characteristics such as strength, corrosion behavior, mouldability and welding capability make steel a perfect material e.g. for stand bases and rods.

• Malleable cast iron: Malleable cast iron is post-treated unter certain conditions after casting. By tempering at 1060° C over a period of three days, malleable cast iron becomes hard and resistant. Double bossheads, clamps etc. may be made of malleable cast iron.

• Aluminium: Aluminium is a metal known for its light weight. However, aluminium has a lower load bearing capacity than cast iron or stainless steel and also aluminium is not very resistant to corrosion. An aluminium structure ages in a laboratory and loses stability. This needs to be considered when using bossheads and clamps for bigger structures with hazardous or valuable substances.

• Nickel: The alloy nickel is known for its shiny, metallic, silvery appearance. If nickel is heated in air, corrosion occurs. However, under inert gas nickel is corrosion-free.
Nickel is mainly used for instruments and containers in analytics as well as for steel finishing. To this end, a purity of 99.5% is crucial. Crucibles, bowls, spatulas etc. are often made of nickel.

• Brass: Alloys with a copper portion between 55 and 90% and a zinc portion between 45 and 10% are referred to as brass. One outstanding characteristic of brass is the excellent mechanical strength (turning, milling, etc.). Gas burners e.g. require optimal tightness and parts turned at a high precision, all parts carrying gas are made of brass. Since brass changes its color, the surface is often provided with a nickel-plating, chromium-plating or other coatings.

• Titanium: Titanium is recommended for applications where high corrosion-resistance, strength and low weight are needed. Further, the metal features ductility and thermal resistance. Titanium has a white-metallic shine, for a quick identification the titanium products are anodized – that is why the instruments appear blue. Titanium is resistant to diluted sulphuric acid, hydrochloric acid, solutions containing chloride, cold nitric acid as well as most organic acids and alkaline solutions, such as sodium hydroxide. Due to the complicated production process, titanium is ten times as expensive as common steel. Products commonly made of titanium are e.g. forceps & tongs, spatulas and scissors.

Surface finishing refers to all technical processes applied during the production of a part to improve its functional surface characteristics, e.g. application of metallic coatings (galvanizing, chromium-plating or nickel-plating), application of organic coatings (painting, powder-coating or plastic coating, e.g. with PTFE), electrolytic polishing (stainless steel) and anodizing (aluminium). These technical processes enable corrosion protection, coating protects against wear and contamination.

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