Cleaning corrosion/oxidised stain on Noctua D-15S heatsink

[MIRTAZAPINE]

Today disassemble my pc to clean of the dust and everything in my itx pc. I realised that my d15s heatsink have to solid white powder stain at the tips of the fins. I could not wipe it out with a micro fiber cloth. And I am unable to scratch it off with my nail, it looks pretty rock solid. Do you know what is it and how to remove it?

 

[Arrakis9]

Dunk one tower at a time into some white vinager for about 10 or so minutes, then rinse with water. You might have to repeat this process a few times.

It might also help to use N old toothbrush to scrub the surface of the fins while it is soaking in the vinager bath.

 

[Gorstak]

those are too gentle for rubbing with something hard. You might bend them or brake them or if you use some liquid, they will change it's colour. I'd leave it as it is.

 

[MIRTAZAPINE]

@Arrakis9

Would the nickel plating be stripped off if I did that? I remember putting my rusted dvd drive cover plate in vinegar, it stripped of the rust but it also stripped of the coating to bare metal. It rusted worse after that. I find it strange how this stain happen to the plated heatsink especially my tower coolers. Stock intel heatsink don't seem to suffer from it.

 

[hat]

You probably already know this but it's purely a cosmetic issue, shouldn't affect performance in any way...

 

[silentbogo]

Dunk one tower at a time into some white vinager for about 10 or so minutes

NO! It may damage nickel-plated layer and maybe even cause some black spots to appear on heatpipes. Also not good for aluminium.

oday disassemble my pc to clean of the dust and everything in my itx pc. I realised that my d15s heatsink have to solid white powder stain at the tips of the fins.

That white powdery stuff is aluminium hydroxide, which probably appeared from too much moisture in the air. Yesterday I was cleaning customer's ROG laptop from this crap (for some reason it spent nearly 6mo in the garage).
You may attempt to remove it with a toothbrush, but it won't be permanent. Even if you have some small amount left, it will be enough to propagate growth in the future. The best thing you can do is give it an ultrasonic bath. If you know anyone in automotive repair business, those guys may have a bath large enough to fit the heatsink.
All you need to do afterwards is spray it with some anti-corrosive stuff (if you are not afraid of smell, then even a WD40 will do).
If ultrasonic bath is not an option, then WD40+toothbrush and probably half an hour of manual labor. You'll probably scratch the surrounding fins in the process, but that's still better than corrosion.

 

[flmatter]

WD40, PB blast, any other anticorrosive spray( quite a few out there) will do. Napa or Autozone has a lot. Also Aluminum prep spray can work as well if you can not find a ultrasonic bath. @silentbogo said it best with ultrasonic bath.
Also check with any powder coat or cerakote business in town they may have a ultrasonic cleaner

 

[plonk420]

pretty sure WD40 will attract dirt and dust like hell

 

[micropage7]

Dunk one tower at a time into some white vinager for about 10 or so minutes, then rinse with water. You might have to repeat this process a few times.

It might also help to use N old toothbrush to scrub the surface of the fins while it is soaking in the vinager bath.

Yep try first with vinegar

 

[Vario]

Don't do anything to it. Its fine. Probably the fans abraided some Nickel? anti corrosion coating/plating off so you have a small amount of aluminum oxide. It doesn't matter one bit.

 

[John Naylor]

SilentBogo got it right ... The heat sink is not nickel, it;'s aluminum and aluminim reacts with moisture to form aluminim oxide. You will find this and other compounds inside water loops of AIOs with aluminum rads.

1. Is it reducing cooling performance ? yes, the oxide is acting like an insulator

2. Is it a concern ? No, it's covers such a small area, that the % impact is miniscule.

If it is aesthetically objectionable ....

1. Remove cooler
2. Wipe TIM with 90%+ isoprophyl alcohol till clean
3. Get a tupperware or container, fill with solution of vinegar and water and insert up side down covering affected areas.
4. Wait 10 minutes, clean with stiff non metal brush or use small plastic scraper / spatula like thingie (available at hardware store) to remove.
5. Rinse with water... dry with fan.
6. Grab a good TIM (Shin Etsu $4 at Directron) and reinstall
7. Get a dehumidifier

 

[Arrakis9]

@Arrakis9

Would the nickel plating be stripped off if I did that? I remember putting my rusted dvd drive cover plate in vinegar, it stripped of the rust but it also stripped of the coating to bare metal. It rusted worse after that. I find it strange how this stain happen to the plated heatsink especially my tower coolers. Stock intel heatsink don't seem to suffer from it.

There may have been grease/dirt in those exact spots when the heatsink was being electro plated wich would answer why it corroded in the first place. As mentioned by some of the other members there is a possibility for it to strip the nickel off, but you can always dilute the vinager with water and reduce the soak time to help mitigate that issue. At this point it's entirely up to you if you wnat to chance it. Personally I would just leave it be and slap the fans back on it and not worry about it.