DeepCool LT720 issue?

[Alfred Stoppels]

Lo Peepz,

Along with loads of other parts I got myself a DeepCool LT720.
My choice was to use THermal Grizzly paste with it so I cleaned the cooler block.
Used the proper alcohol and soft papercloth for it.

What I then found is seen on the picture below. I am 100% sure I did not cause it, it just revealed while cleaning it.
Any idea how this could have happened (testing example maybe)?
Second question: Is this a problem?

The AIO did not look used when the paste was still applied, it was spotless.

 

[Vya Domus]

I recall seeing something similar when I changed my CPU and cleaned the paste after about 3 years, I guess it just stains over time. Shouldn't matter.

 

[Alfred Stoppels]

Stains? ... hmm, it was brandnew, bought it a week ago

 

[Vya Domus]

Stains? ... hmm, it was brandnew, bought it a week ago

Yeah but I mean it could stain it regardless, it kind of looks as if you just swiped away something and it left some marks.

 

[Alfred Stoppels]

Could accept that if I realy scrubbed it hard but I didnt. Just gentle with only soft material. Became vissible already after the first whipe

 

[Bill_Bright]

Copper begins to corrode almost immediately after exposure to air (oxygen). Can you feel scratches or irregularities with your finger? If not, I would not worry about it. HOWEVER, since you just tried to feel for scratches, you just deposited skin oils on it so you need to clean it again. I would NOT however, use papercloth (whatever that is) - unless specifically designed for eyeglasses and from a reputable company like Bausch & Lomb. I use a clean, microfiber cloth designed for eyeglasses.