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STAINLESS STEEL EQUIPMENT CARE AND CLEANING
(Supplied courtesy of NAFEM. For more information, visit their web site at www.nafem.org)
Contrary to popular belief, stainless steels ARE susceptible to rusting.
Corrosion on metals is everywhere. It is recognized quickly on iron and steel as unsightly yellow/orange
rust. Such metals are called "active" because they actively corrode in a natural environment when their
atoms combine with oxygen to form rust.
Stainless steels are passive metals because they contain other metals, like chromium, nickel and manganese
that stabilize the atoms. 400 series stainless steels are called ferritic, contain chromium, and are magnetic;
300 series stainless steels are called austenitic, contain chromium and nickel; and 200 series stainless,
also austenitic, contains manganese, nitrogen and carbon. Austenitic types of stainless are not magnetic,
and generally provide greater resistance to corrosion than ferritic types.
With 12-30 percent chromium, an invisible passive film covers the steel's surface acting as a shield against
corrosion. As long as the film is intact and not broken or contaminated, the metal is passive and stain-
less. If the passive film of stainless steel has been broken, equipment starts to corrode. At its end, it rusts.
Enemies of Stainless Steel
There are three basic things which can break down stainless steel's passivity layer and allow corrosion
to occur.
•
Mechanical abrasion
•
Deposits and water
•
Chlorides
Mechanical abrasion means those things that will scratch a steel surface. Steel pads, wire brushes and
scrapers are prime examples.
Water comes out of the faucet in varying degrees of hardness. Depending on what part of the country you
live in, you may have hard or soft water. Hard water may leave spots, and when heated leave deposits
behind that if left to sit, will break down the passive layer and rust stainless steel. Other deposits from
food preparation and service must be properly removed.
Chlorides are found nearly everywhere. They are in water, food and table salt. One of the worst chloride
perpetrators can come from household and industrial cleaners.
So what does all this mean? Don't Despair!
Here are a few steps that can help prevent stainless steel rust.
1.
Use the proper tools.
When cleaning stainless steel products, use non-abrasive tools. Soft cloths and plastic scouring pads
will not harm steel's passive layer. Stainless steel pads also can be used but the scrubbing motion
must be in the direction of the manufacturers' polishing marks.
2.
Clean with the polish lines.
Some stainless steel comes with visible polishing lines or "grain." When visible lines are present,
always scrub in a motion parallel to the lines. When the grain cannot be seen, play it safe and use
a soft cloth or plastic scouring pad.
3.
Use alkaline, alkaline chlorinated or non-chloride containing cleaners.
While many traditional cleaners are loaded with chlorides, the industry is providing an ever-increasing
choice of non-chloride cleaners. If you are not sure of chloride content in the cleaner used, contact
your cleaner supplier. If your present cleaner contains chlorides, ask your supplier if they have an
alternative. Avoid cleaners containing quaternary salts; it also can attack stainless steel and cause
pitting and rusting.
All manuals and user guides at all-guides.com
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