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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 fi lm covers the steel's surface acting as a shield
against corrosion. As long as the fi lm is intact and not broken or contaminated, the metal is passive
and stain-less. If the passive fi lm 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.
1.
Mechanical abrasion
2.
Deposits and water
3.
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.
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DIRECT STEAM KETTLES
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