If you look at the pushPIN series Brass push pins from Advanced Thermal Solutions, you may see that the surface of the device displays discoloration.
Verified by the manufacturer, the push pins of this series are made from a brass alloy. The discoloration is completely normal tarnishing, and is only superficial (it does not affect the underlying metal).
There is no further documentation on this, because the parts appear normal and within specification. (The specification being plain brass finish, no plating)
For reference:
What is Brass? an in depth technical guide
How Fast Does Brass Tarnish – An Overview
What Causes Brass to Corrode and How to Bring Back Its Lost Luster
More information about the push pin selection for ATS Heatsink
Finding a Push Pin and Spring for ATS Heat Sinks
Applicable part numbers
| DK Part # | Mfr Part # |
|---|---|
| ATS1880-ND | ATS-PP-01 |
| ATS1881-ND | ATS-PP-02 |
| ATS1882-ND | ATS-PP-03 |
| ATS1883-ND | ATS-PP-04 |
| ATS1884-ND | ATS-PP-05 |
| ATS1885-ND | ATS-PP-06 |
| ATS1886-ND | ATS-PP-08 |
| ATS1887-ND | ATS-PP-09 |
| ATS1910-ND | ATS-HK91-R0 |