How to remove oxidation from new rads?

Drangueos · 25 Jun 2014 at 16:06

I bought 3 new XSPC radiadors, 2x AX360 and 1x AX120 and you can see the oxidation on the cores.

What is the best and safest way to remove the oxidation?

You can see the difference in color between them, the oxidation on the AX120 is not as bad as the AX360s.

rads:
http://www.overclockers.co.uk/showproduct.php?prodid=WC-180-XS&groupid=962&catid=1523&subcat=1526
http://www.overclockers.co.uk/showproduct.php?prodid=WC-175-XS&groupid=962&catid=1523&subcat=1524

Finners · 25 Jun 2014 at 16:40

Do you mean on the actual copper fins? I can't imagine there is much you can do as they are so fragile.

red eye · 25 Jun 2014 at 16:49

Soak in ketchup?

Shawy · 25 Jun 2014 at 17:02

I wouldn't bother with it tbh. But if you must, ketchup should do the job but it'd be awfully messy.

Minstadave · 25 Jun 2014 at 17:02

I would just use them as is. It's cosmetic and they'll be covered in dust as soon as you use them anyway.

Meoricin · 25 Jun 2014 at 18:53

Doesn't white vinegar work the same way as the ketchup? Would be much more pleasant to use that then rinse with isopropyl.

Drangueos · 25 Jun 2014 at 20:12

I was thinking about vinegar and rinse with deionized water, because I want to paint the core, so I think would be better to remove the oxidation before painting.

paulstung · 27 Jun 2014 at 17:28

What paint do you intend to use on the core ? As you need to be very specific with what you use as not to imped the cooling performance.

Drangueos · 2 Jul 2014 at 22:59

paulstung said:
What paint do you intend to use on the core ? As you need to be very specific with what you use as not to imped the cooling performance.

with this: http://www.overclockers.co.uk/showproduct.php?prodid=CM-000-MN

ubersonic · 2 Jul 2014 at 23:45

I'm really not sure what to recommend, copper/brass cleaner like Brasso would do the trick but you can't physically clean the fins so you need something you could just soak it in that would attack the patina but not the copper.

*EDIT*

XSPC claim they are "passivated to slow oxidation" which put simply means they come pre-oxidised to shield them from further oxidation.

shadowscotland · 3 Jul 2014 at 08:42

you want them to oxidize - shiny is bad for radient heat transfer.
Higher the emissivity the better
shiny copper - 0.05
thick oxide layer - .78 (that over 10x better)

and unlike paint that has a slight insulation value, the oxide layer is chemically part of the metal

rads are usually painted with a thin layer of black paint - 0.8
but if you can find a Black Epoxy Paint (0.89) or Matt Black Silicone Paint (0.93) that's even better.
Spray cans are available for use on engine blocks / exhaust headers etc

what I don't know is if the oxides act to protect the metal underneath (like aluminum)
or it just keeps eating the metal like in iron / steel
As copper is non-ferrous like aluminum I guessing it a barrier to further corrosion

Edit: it's a protective patina or Pilling–Bedworth ratio of 1.75 (below 1 bad, above 2 bad)

ubersonic · 3 Jul 2014 at 09:05

shadowscotland said:
you want them to oxidize - shiny is bad for radient heat transfer.

Not really true, patina has minimal effect on direct heat transfer like a heatsink or CPU block, but in the case of radiators which heat mostly via convection (the name is a misconception dating back to the 1800's) it impedes heat transfer and can have quite a serious effect in severe cases hence why radiators are normally protectively coated.

shadowscotland said:
what I don't know is if the oxides act to protect the metal underneath (like aluminum)

I would guess so as XSPC pre-oxidise these radiators to protect them from further oxidation.

Minstadave · 3 Jul 2014 at 09:08

Surely radiant heat transfer is irrelevant for a radiator, it'll be conduction and convection largely.

shadowscotland · 3 Jul 2014 at 11:09

Reading some more I agree the crystaline structure of the oxide will impede conduction of heat from metal to air (significantly reduced the thermal coefficient).

And I guess thinking about it more any radient heat loss from the fins will be reabsorbed by the fins opposite (been using radient panels in my passive loops for two long)

But once the heat /energy is in the air, the oxide should not affect convection in any way. (copper oxide doesn't form massive flakes like rusty iron)

conduction (heat from rad to air)
Convection, fan assisted (air to outside case)