This article explains if copper oxidation may impact the cooling performance of water-cooling products made of copper.
Copper Oxidation and Performance
Copper does not react with water. Instead, it slowly reacts with atmospheric oxygen forming a layer of brown-black copper oxide. In contrast to the iron oxidation process by humid air, this oxide layer stops further bulk corrosion.
A green layer of verdigris (copper carbonate) can often be seen on old copper constructions. Water cooling equipment usually tarnishes when exposed to sulfides that react with it to form various copper sulfides.
Tarnished copper may look discouraging, but it has no measurable impact on performance - the oxidation layer is too thin to have any effect on thermal conductivity.
The photo above illustrates oxidized water block copper base (source: overclock.net)
Can I Prevent Copper Oxidation?
It is nearly impossible to avoid naturally occurring copper tarnishing (oxidation). However, it's recommended to use nitrite or latex gloves during installation as human skin oil is slightly acidic. Those who don't prefer the looks of tarnished copper are advised to use nickel-plated copper water blocks.
The use of quality market-proven biological growth- and corrosion-inhibiting coolants is always strongly recommended for any liquid cooling system.
For best results, EK recommends the use of EK-CryoFuel Coolants.