Frequently Asked Questions

1. What is stainless steel ? Stainless Steel is the generic name given to a family of corrosion resistant metallic alloys, that generally contain more than 11% of Chromium. There are many different grades of stainless steel, each being manufactured for specific applications. 2. Why would I use stainless steel? Stainless steel is predominantly used where corrosion resistance is required. There are four main groups of stainless steel. Those being (a) Austenitic (b) Ferritic (c) Martensitic, and (d) Duplex. The stainless steel grades within those four groups have individual properties. Therefore, the choice of the correct grade of stainless steel, would very much depend on its application of service. 3. What causes stainless steel to tarnish and stain? Like all metals, Stainless Steel is protected by a thin outer layer, called the oxide layer. Mechanical processes such as grinding, polishing, welding, machining etc, will remove this oxide layer and expose the material to air-borne contaminants and aggressive environments, such as sea front and swimming pools. Consequently the use of mechanical processes can actually accelerate the corrosion process. 4. How do I remove stains and tarnishes from stainless steel ? Surface stains and tarnishes, can be removed by chemical dissolution. This is best carried out by using a non-hazardous cleaning solution called WILLOWCHEM 61. This solution will remove surface staining and should be rinsed after use and accompanied by the application of WILLOWCHEM BIOPASS solution, which will restore the protective oxide layer. 5. What is Electro-polishing ? Electro-polishing is an electrochemical process similar to, but the reverse of, electroplating. The process provides maximum corrosion resistance to the surfaces of stainless steel components. The most noticeable benefits of the process is the resulting bright and decorative appearance to the processed component. However, the metallurgical benefits are far more beneficial, leaving the material hygienically pure and highly corrosive resistant. The process is carried out by the immersion of the product in an electrolyte, WILLOWCHEM 90, which makes the process very cost effective and very versatile. 6. Why Electro-polish Stainless steel ? As well as being aesthetically bright, the metallurgical benefits of electro-polishing are far more substantial. After electro-polishing, the stainless steel material is rendered hygienically pure and highly corrosive resistant. The process is very cost effective and very versatile. Therefore, electro-polishing should be considered where maximum material corrosion resistance is beneficial and where bacterial formation is undesirable. 7. What is Passivation ? Passivation is a post fabrication / machining process, which greatly improves the corrosion resistance of the stainless steel material. The process is carried out by the dissolution of any surface iron compound (free iron), by using an acid solution, most commonly Nitric Acid, typically WILLOWCHEM 70. Thus creating a spontaneous, passive film on the surface of the stainless steel component. 8. Why Passivate Stainless steel ? Many fabricators, manufacturers and workshops that use Stainless steel, do not fully appreciate the fundamental metallurgical requirements needed to achieve fit for purpose components and as a consequence, readily turn their backs on the resulting problems that can occur from that lack of knowledge. The aftermath can be extremely costly, frustrating and sometimes very difficult to remedy after installation or service. The Passivation and / or Electro-polishing process can eliminate these needless risks and enhance product quality and sustainability. 9. How do I get the best sustainable life cycle from my Stainless Steel fabrication ? In general and harsh environments, an Electro-polished component will provide a corrosion resistance of up to 30 times that of an un-treated component. Therefore, wherever possible, Electro-polishing or passivation should be considered for any stainless steel component that will be subjected to corrosive elements, such as outdoor, marine, chemical, food, saline or other aggressive conditions.