Mechanical Brushed (Satin Line)
Linear satin scratches formed mechanically using abrasive belts. Widely used in consumer electronics and appliance panels.
Key Parameters
Recommended Base Materials
Stainless steel chassis, aluminum front panels, appliance surfaces
Pairs with these materials
What to specify on your drawing
- Grain direction per face — horizontal and vertical brushed faces read completely differently on a cabinet
- Which faces are cosmetic: brushed faces show handling marks, so cosmetic faces get protection through fabrication
- No. 4 versus hairline — similar names, different look; a physical or referenced sample settles it
- Whether welds on brushed faces are to be blended and re-grained, or left as-is
Factory Work Sequence
Fixturing parts on conveyor for consistent contact pressure
Progressive belt grinding with 180-320 grit abrasive belts
Post-brush passivation for stainless steel corrosion resistance
Advantages
- Consistent directional grain pattern hides fingerprints and minor scratches
- Low cost, fast processing, and scalable to high-volume production
- Can be combined with clear coating for enhanced durability
Limitations
- Directional grain must align with part geometry — cross-grain marks reject parts
- Not suitable for deep-drawn or curved surfaces where grain uniformity is difficult
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Also in this category
Brushed finishing produces a directional satin grain by running an abrasive belt or wheel across the surface. It is the standard way to make weld dressing and handling marks disappear on stainless steel, and it produces a finish that fingerprints show less than on a polished surface.
Grain direction is part of the specification
A brushed surface has a direction. Run the grain horizontally across a panel and the eye reads a consistent line; run it in two directions on one face and the panel looks patchy under any raking light. Which way the grain runs belongs on the drawing, because it is visible in the finished product and cannot be corrected afterwards.
Hairline and No. 4 are not the same finish
A No. 4 finish is a coarser, more visible grain produced with a relatively coarse abrasive. A hairline finish is finer and produces a much subtler line. Both are commonly called "brushed", and specifying one when the customer wanted the other is a finish that cannot be reworked out — the part has to be re-finished from a coarser step.
Brushing is how weld dressing is hidden
On a visible stainless weld, the sequence is weld, dress the bead flush, then blend the dressed zone to the parent surface. A brushed grain across both makes the transition invisible. Skip the blending step and the dressed area reads as a different shade even though it is dimensionally flush, because the surface texture differs.
Where a brushed finish is the wrong answer
It is a mechanical finish on the surface, so it offers no additional corrosion protection and cannot be applied to a coated or plated part without removing the coating. On an outdoor part, brushing alone leaves the surface vulnerable at every scratch; the stainless grade has to be selected for the environment separately.
Finish specified against substrate and purpose
| Finish | Typical substrate | Character |
|---|---|---|
| Hairline | 304 / 316 stainless | Fine, subtle directional grain |
| No. 4 | 304 / 316 stainless | Coarser, more visible grain; the industry default |
| Bead blasted | Stainless, aluminium | Non-directional matte; hides handling marks |
| 2B mill finish | Stainless (as supplied) | Smooth matte from the mill; no additional operation |
| Brushed over aluminium | 5052 / 6061 | Possible, but anodizing is usually preferred |
Specifications this finish is worked to
These are specifications the finish is specified against. They are not certifications held by WERIX — ISO 9001 is the only management-system certification we hold.
What to put on your drawing
- Which faces are brushed and which are left at mill finish.
- The grain designation — hairline or No. 4.
- The grain direction, per face where it differs.
- Whether weld-dressed zones are to be blended to a single texture.
- Whether the environment requires a further treatment over the brushed surface.
Frequently asked
What is the difference between hairline and No. 4 finish?
Grain coarseness. No. 4 is produced with a coarser abrasive and gives a more visible line; hairline is finer and subtler. Both get called "brushed" in conversation, which is why the designation belongs on the drawing rather than in an email.
Does a brushed finish improve corrosion resistance?
No. It is a mechanical surface texture and adds no protective layer. Corrosion resistance comes from the alloy, so the grade has to be chosen for the environment separately — brushing only changes how the surface looks.
Why does brushed stainless show fewer fingerprints than a mirror finish?
Because the directional grain scatters light and breaks up the reflection that makes a fingerprint visible on a polished surface. That is one of the practical reasons brushed finishes are specified on touch surfaces.
Can a brushed finish hide a weld?
It can make a dressed weld invisible if the grain is run continuously across the dressed zone, blending it to the parent metal. That requires the weld to be dressed flush first; brushing cannot hide a bead that stands proud.
Related reading
Finish guides
Read the Brushed guide
The specs, standards and drawing notes above give the numbers. The guide gives the reasoning behind them — how the finish behaves on the shop floor, where it fits, and where it does not.