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The Technology Behind Our Stainless Steel

Three things set our stainless steel apart: PVD color coating that is thicker and more consistent than typical market product, anti-fingerprint coatings that keep surfaces clean with one wipe, and production tested to recognized national and international standards. Each one is shown below with real measurements.
PVD coating  ·  Anti-fingerprint  ·  Recognized standards  ·  Every figure names its test method
PVD coating standard

Thicker coating, tighter color, tested on every order

We color stainless steel two ways: full coils for standard PVD colors, and sheet by sheet for special colors and small batches. The figures below are measured on our coil-coated production, against typical market product.
0.30µm
Typical coating thickness, 0.25 µm minimum
A thicker film takes longer to wear through to the steel. Typical market coating: 0.21–0.27 µm.
3,500+
MEK solvent rubs without wearing through
A strong solvent rubbed back and forth over 3,500 times, and the color stays on. Typical market coating: just over 3,000.
10/ 10
Neutral salt spray rating, GB/T 10125
The top rating after salt spray testing: no visible corrosion on the coating, so it holds up in humid and coastal spaces.
±1
LAB color tolerance on a* and b*
Sheets from different coils look the same: color drifts at most 1 point either way, below what the eye can see.

Ahead of typical market product on every test

Same tests, side by side, on coil-coated PVD. The same standard applies to titanium gold, rose gold, black and every other coil color.
Salt spray is rated 0 to 10. A rating of 10 means no corrosion.
Property
Sanmei Metal PVD
Typical market
Coating thicknessCalotest (ball cratering)
≥ 0.25 µmtypically 0.30–0.32 µm
0.21–0.27 µm
MEK solvent rubWear and cleaning-agent resistance
> 3,500 rubs
> 3,000 rubs
Neutral salt sprayGB/T 10125 (≈ ISO 9227)
Rating 10
Rating 9
AdhesionGB/T 5270 cross-hatch
No flaking
Up to ~5% flaking
Color toleranceSpectrophotometer, CIE LAB
±1 a* / b*±2 L* on dark tones
Often unspecified

Up to 28% thicker coating, so the color lasts longer

Measured under the microscope with the ball-cratering method: a steel ball grinds through the coating, and thickness is calculated from the ring it leaves. 0.301 µm on our coil-coated titanium gold, 0.235 µm on a typical market coil.
Titanium Gold
+28% coating
ti gold coating of pvd sheets under microscope in market
Typical market
0.235 µm
ti gold coating of pvd sheets under microscope in sanmei metal
Sanmei Metal
0.301 µm
Rose Gold
+28% coating
rose gold coating of pvd sheets under microscope in market
Typical market
0.250 µm
rose gold coating of pvd sheets under microscope in sanmei metal
Sanmei Metal
0.319 µm

Color difference held below ΔE 2: no difference you can see

Reorder next year or mix coils on one wall, and the sheets still match. Every standard PVD color is held at ΔE 2 or less, the level below which most people see no difference.
ΔE ≤ 2
Most suppliers give no color tolerance at all, so a mismatch only shows once the panels are on the wall. We set a measured limit for every color and check it by instrument, never by eye.

Our limit for each standard color

Color · click to view
Target value
Allowed range
Max. ΔE
To the eye
Titanium Gold→
b* 32
±1
1.0
Not visible
Rose Gold→
a* 12, b* 22
±1 each
1.4
Not visible
Black→
L* 47 mirror / 40 hairline
±2
2.0
At the limit
Titanium Gold, anti-fingerprint→
b* 33–34
±2
2.0
At the limit
Black, anti-fingerprint→
L* 35
±2
2.0
At the limit
Click a color name to open its product page, with sizes, finishes and samples.
Max. ΔE is the worst case, with every value at the edge of its range at once. Rose gold: √(1² + 1²) = 1.4. Black only varies in L*, so its worst case is 2.0.

Checked twice, by instrument

inline LAB mobitoring in sanmei metal
Step 1 · on the coating line
Inline monitoring
A LAB sensor reads the coil continuously while it is coated. If the color starts to drift, the line is corrected before the coil is finished.
LAB mobitoring in sanmei metal
Step 2 · after coating
Offline check
Finished coils are measured again with a handheld spectrophotometer to confirm the color matches its target.

Special colors: matched to a recorded reference

For special colors and small batches, we coat individual sheets on mirror, hairline, cross hairline or sandblasted base. Each color has a recorded LAB reference, and coated sheets are measured against it. You can also send an approved sample as the target.
Purple Mirror Stainless Steel Sheet S26MR-17
Purple
Mirror
L* 50.73 · a* 11.38 · b* 0.06
View Mirror sheets→
rose gold stainless steel sheet
Rose Gold
Hairline
L* 55.21 · a* 12.10 · b* 11.27
View rose gold sheets→
Titanium Gold Hairline Finish Stainless Steel S26HL-06
Titanium Gold
Hairline
L* 71.90 · a* 3.86 · b* 35.49
View titanium gold sheets→
PVD Black Titanium Hairline Stainless Steel Sheet S26HL-11
Black
Hairline
L* 35.76 · a* -0.10 · b* 0.50
View black sheets→

What does ΔE mean? A quick guide

ΔE < 2
Most people see no difference
Where every PVD color we supply is held.
ΔE 2–5
Visible with two sheets side by side
Shows on a wall built from mixed batches.
ΔE > 5
Reads as a different color
A rejected batch on any project.
New to color measurement?

What do L*, a* and b* mean?

Color is not judged by eye. A spectrophotometer reads every surface as three numbers in the international CIE LAB color system.
L* · Lightness. 0 is black, 100 is white. A lower number means a darker sheet.
a* · Green to red. Below 0 leans green, above 0 leans red. Rose gold has a high a*.
b* · Blue to yellow. Below 0 leans blue, above 0 leans yellow. Gold has a high b*.

How is ΔE calculated?

ΔE (delta E) turns the differences in L*, a* and b* into one number. Measure the target and the actual sheet, subtract each value, square the three differences, add them, and take the square root.
ΔE = √( ΔL*² + Δa*² + Δb*² )
Example, rose gold:
 
L*
a*
b*
Target
68.0
12.0
22.0
Sheet measured
68.0
12.8
21.4
Difference
0
0.8
−0.6
ΔE = √(0² + 0.8² + 0.6²) = √1.00 = 1.0, below 2, so no visible difference.

Can you match a color sample we already approved?

Yes. Send the approved sample. We read its LAB values and use them as the production target, with the same tolerance shown above.
Tell us about your project

Fingerprint-resistant surfaces that wipe clean

An anti-fingerprint (AF) coating is a clear top layer over the PVD color. Fingerprints barely show, and one wipe cleans the surface. Our standard AF withstands 215 solvent wipes; typical market AF wears through at 70.
Roll-coated, over 2 µm thick · tested to YB/T 4333

Standard AF

Test
Sanmei
Typical market
Coating thicknessA thicker film lasts longer
> 2 µm
< 2 µm
Butanone (MEK) rubSolvent wipes before the film wears through. Required: over 100
215
70
Pencil hardnessScratch resistance. 3H is harder than 2H
3H
2H
Cupping testHow deep the sheet can be pressed before the film cracks
> 8 mm, no crack
Cracks at 7 mm
90° T-bendSheet bent to 90°, checked for cracks
No crack
Slight cracking
Under 20 nm thick · no color shift

Nano AF

Water contact angle
> 115°
Water beads up and rolls off
Pencil hardness
> 6H
Very high scratch resistance
Salt spray, acid, alkali
> 48 h
No damage after 48 hours
Heat resistance
250 °C
Held for 100 hours
Artificial sweat
> 72 h
Resists skin oils and sweat
After steel wool rubbing
> 90°
Still repels water
Used on range hoods, dishwashers, cooktops, grease filters and product panels. Available on titanium gold, rose gold and black PVD finishes.
Tested on our own sheet

Marker and steel wool test: lower upkeep, on camera.

We put our anti-fingerprint coating through two everyday abuse tests and filmed the results, so you can judge the surface yourself before ordering.
Marker pen test: we draw on the coated surface with a marker, then wipe it. Watch how the ink lifts off without solvents or scrubbing.
Steel wool test: we rub the coated surface with a steel wool pad to check how the coating holds up against abrasion.
What it means for upkeep: fingerprints, marks and graffiti clean off faster, with less frequent deep cleaning — lower maintenance cost over the life of the panel.
Tell us about your project

Made and tested to recognized standards

Base steel, coating and corrosion tests follow Chinese national standards. Where an international equivalent exists, it is shown next to the code, so your team can match it to the specs they already use.

Base steel

GB/T 3280
Cold-rolled stainless steel plate, sheet and strip
T/FSMA 002-2018
Cold-rolled austenitic stainless steel decorative sheet
GB/T 222
Permitted deviations in chemical composition of steel products

Coating performance

GB/T 7707
Ion-plated coating thickness, ball-cratering method
GB/T 5270≈ ISO 2819
Adhesion test methods for metallic coatings
GB/T 9754≈ ISO 2813
Specular gloss at 20°, 60° and 85°

Corrosion

GB/T 10125≈ ISO 9227
Salt spray testing in artificial atmospheres
GB/T 6461≈ ISO 10289
Rating of coated specimens after corrosion tests

Finishing & delivery

YB/T 4333
Anti-fingerprint stainless steel decorative sheet
GB/T 2480
Silicon carbide abrasives for surface finishing
GB/T 247
Packing, marking and quality certificates for steel sheet and strip
Tell Us About Your Project
Every order ships with a Mill Test Report. SGS test reports and LAB color readings are available on request.

Contact us

Creating Center, Shunde District, Foshan City, Guangdong Province, 528315, China
+8615015653566 / 0757-87668353
Paige Deng
marketing@sanmeimetal.com

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    TEL: +8615015653566 / 0757-87668353
    Email: marketing@sanmeimetal.com

    Headquarters:
    Creating Center, No.142, Yuhe Road, Lecong Town, Shunde District, Foshan City, Guangdong Province, China. 528315

    Factory: Liyuan Logistics City, Chencun Town, Shunde District, Foshan City, Guangdong Province, China. 528313

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