|
The following information is provided
courtesy of The Catering Equipment Suppliers Association.
Understanding
Stainless Steel
Stainless
steel is one of the main construction materials of every
professional kitchen. It is tough, easy to clean and resistant
to corrosion. It used in cutlery, prime cooking equipment and
utensils, but its most visible use is in shelving, tables and
sinks. Not the most glamorous areas of the kitchen, but where
stainless steel plays a pivotal role in durability of work
surfaces and kitchen hygiene.
Steel is
made by mixing molten iron with carbon in a furnace. Adding the
carbon gives greater strength, but does not overcome the problem
of rusting. By adding nickel, chromium or both metals to the
molten iron in addition to carbon, rusting can be controlled,
though not totally eliminated.
There are
international standards laid down for the making of stainless
steel so that metal from different parts of the world is
consistent. The two main grades of stainless steel used in
catering equipment are grade 304 and grade 430. The grade rating
indicates the mix of metals in the stainless steel alloy.
Grade 430 is
the cheaper stainless steel, containing just chromium. Grade 304
contains both chromium and nickel and is more corrosion
resistant, but more expensive.
The benefit
of 430 stainless steel is that being cheap, it is useful for the
manufacture of tables and pressings such as sinks where low cost
is an important part of the specification, but corrosion will be
a problem in the long term.
Another
important consideration when buying stainless steel tables and
sinks is the thickness of the steel. A thin gauge metal will not
be as durable as a thick one. The usual thickness for stainless
steel tables and sinks is 1.2mm. It is possible to buy .9mm
stainless steel, but don’t expect a long life from it. The top
end of stainless steel for very heavy use is 1.5mm thickness.
One way of making a medium thickness stainless steel used in
tabling much stronger is to seal in a layer of medium density
fibreboard (MDF). This manufacturing process also reduces
vibration and noise.
There are no
international standards on the polished finish of stainless
steel, but there are manufacturer descriptions which indicate
the type of surface. Satin finish is a fairly dull looking
surface which is suitable where the appearance of the tabling or
sinks is not important. This is a very hard-wearing surface
which does not show scratch marks as much as a highly-polished
stainless steel.
A high
polished finish is often used where the stainless steel is on
public display such as in serveries and counters, though for
economy reasons, the underside may be satin finish. The
stainless steel finish gaining popularity for its looks and ease
of cleaning has the generic name of superbrush. This has a close
grain finish, does not show fingerprints so easily and is easier
to keep clean than other stainless steel surfaces.
Popular logic
says that pressing a sheet of stainless steel to form sinks or
tabling will produce weak spots in the bends. The science of
metal says different and folds in metal can actually increase
the strength. Where weak points in the fabrication can occur is
with cheap welding. With 304 stainless steel it is important
that the welding rods are also 304 stainless to avoid the weld
becoming a vulnerable area.
One of the
principal benefits of stainless steel is its ability to keep
clean, yet with sinks and work tables, the cleaning is often the
cause of damage. No detergent with bleach or any chlorine
content should be used on stainless steel. Chlorines attack the
surface of stainless steel and will lead to rust spots. The best
way to clean any stainless steel table or sink is soap and hot
water. Harsh abrasives such as wire wool pads will also damage
stainless steel. Nylon scouring pads are better, but if they are
too rough they will still score the surface and spoil the
polished sheen.
|
