Appearance influences many characteristics. How do you choose the best surface for every use among the many different finishes?

1. Mechanical finishes of
stainless steel
Appearance influences many characteristics.
How do you choose the best surface for every
use among the many different finishes?

2. Stainless steel, unlike other metals, contains a certain percentage of chromium.
This alloying element creates a film of protective oxide, a few atoms thick.
Despite being very thin it is very resistant and prevents corrosion. Also it
regenerates itself: if it is removed or damaged it instantly reforms. For this
reasons, stainless steel can also be used without being painted. There are many
finishes that fit the natural aesthetics of steel to the most different contexts and
uses.

3. Finishes can be divided between mechanical, electrical, electrochemical and
chemical. Below we are going to list only the mechanical ones. The categories
with the number 1 are hot rolled, while those with the digit 2 are cold rolled.
They are categorized in accordance with EN 10088-2. These are the most
common mechanical finishing.

4. Standard mill finishes
1U
Hot rolled sheet, not annealed. Mill scale is not removed. Mainly used as a by-
product.
1C
Hot-rolled sheet, heat treated (annealed). Mill scale is not removed. Mainly used as
a by-product.

5. 1D
Hot-rolled sheet, heat
treated and pickled. It's the
most common finish on high
thicknesses. It's mostly used
on hidden parts because of
its opaque and rough
surface. The D means dull.

6. 2D
Cold-rolled, heat treated
like 1D, and pickled. It's
more refined than 1D.
The dull appearance
limits its usage to non-
decorative uses.

7. 1E
Hot-rolled and heat treated by annealing. Mill scale has been
removed by mechanical means at the discretion of the supplier.

8. 2B
This finish is obtained from
2D with a further rolling with
highly polished rolls. Final
appearance is grey, and can
be used as a starting point
for further polishing or
brushing. It's the most
commonly used finish.

9. 2R
Cold-rolled with polished rolls
and heat treated in controlled
oxygen-free athmosphere.
Material is not damaged so
pickling is not needed. It can
also found under the obsolete
label BA or 2BA (Bright
Annealed). It's largely used
without further processing
because of its appearance and
because it's easy to clean. It's
also used as basis for mirror-
polishing or for colouring.

10. 2H
The H stands for Work (H)ardened, because a specific cold rolling increases the sheet
metal strength. Surface appearance is bright.
2C
Cold-rolled and heat treated. Mill scale is not removed.
2E
Cold-rolled sheet, heat treated. Mainly used on steels that have a hard mill scale that
in this finish has to be mechanically removed.
2Q
Cold rolled and heat treated by tempering. This finish is mostly done on martensitic
steels.

11. Special finishes
1G o 2G
Ground sheet metal, with a unidirectional and rough surface. It's often
possible to specify the grit grade or the desired roughness. Usually only one
face of the sheet is processed.

12. 1J e 2J
Brushed sheet metal,
smoother than 1G/2G.
Also here it's possible to
specify the grit grade or
surface roughness. Mostly
used in interior
architecture.

13. A typical example is the Scotch Brite finish, named after the
fine-grit abrasive material. This finish is used in interior
architecture.

14. 1K e 2K
Polished satin matte finish, similar to 1J/2J but smoother, with a maximum
roughness of 0.5 microns. Usually silicon carbide polishing belts are used,
because alumina (aluminium oxide) weaken corrosion resistance. This type of
sheet metal is mainly used on exterior architecture and marine/seaside areas.
2F
Heat treated by annealing, pickled and then rolled with bead-blasted rolls to
get a dull finish.

15. 1M e 2M
Uniform surface can cause unpleasant deformed reflections. To avoid this effect,
sheet metal with 1M/2M finish are decorated with a textured pattern on one side,
by stamping or rolling. The other side is smooth. Textured sheets also have an
increased rigidity that allows for reduced thicknesses. Many decorations, textures
and patterns are available.

16. 1W e 2W
Like 1M/2M categories, but sheet metal is textured on both sides. Also this
category is widely used in architecture. In some cases, the surface helps making
scratches and dents less visible.
1P/2P
Polished bright stainless steel, non directional, mirror-like. It's the best choice
where corrosion resistance is fundamental. Surface roughness can be specified.
This finish is obtained with polishing felts and specific chemical products.

17. Bead blasting
This finish is not included in EN 10088-2
regulation, but it's widely used. It's similar to
sandbasting in its principle, the difference
being that beads are bigger. They can be
made of different materials like stainless steel,
glass, ceramics, nut shells, aluminum oxide,
according to the desired effect. Bead shape
can be spherical or irregular. Austenitic steels
can see their surface hardness increase with
heavy beads blasting. In some cases, both
surfaces must be treated to balance internal
stresses. Mild steel beads, or other materials
containing iron, must not be used to avoid
stainless steel contamination.

18. Engine turning
This unmistakable effect is obtained by
grinding the sheet metal with rotating
abrasive pads, with a constant offset,
usually 60°. Complicated and custom
patterns and decorations can also be
acheived.

19. Gasparini Industries s.r.l.
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