After doing that picture for the Spyderco Forums….
I have noticed those red dots near the pivot on my Paramillie 2 in 52100.

Some “voiding the warranty” time later I noticed that…

Edited the 2nd of November 2017. This is not the case anymore as stated in Spyderco new warranty:
“If a knife has been disassembled and reassembled correctly—so as to maintain its proper mechanical function—this warranty remains in full effect. “

The problem is not the rust or the patina. 52100 is not stainless.
The problem is the fact that the pivot area is hidden under the scales and that rust can easily develop there without to be noticed.

So the idea is to develop a patina on the whole blade and pivot area, to create a smooth “crust” protecting the surface.

Of course yesterday I have put some vinegar to create my patina and some drops have been near the pivot… It was fast in rusting in that area without patina.

Let’s clean that first. I will use white compound and some paper towels.

As you can notice this is not really deep pitting. There is just some patina forming under.
So now it’s time for a great vinegar bath…. It was really three screws to remove and I had access to the blade. No big deal. Warranty voided easily.

Soaking the blade completely is not the most aggressive way to develop a patina as it needs to form acid and oxygen. It’s better to take the blade out of the bath and envelop it with paper towels. But here I wanted a slow and steady patina. So I let it submerged for one hour.

On the picture above, you can still see the polished edge….

And after one hour of socking : all his grey and my polished edge is also stained gray now. So everything is cover with patina.

Time to put some nano oil in the pivot and around.

Working it an hundred time to smooth it. And cut myself in the process.

Add some Ballistol for good measure and protect the blade. Stropping the blade on leather… The blade is perfectly centered. No play, smooth like on glass. The tolerance are really high in the construction of that knife.

Et voilà: fight rust ! Force patina !!

“52100 Tool Steel
AISI 52100 is a high carbon tool steel containing low quantities of manganese and chromium to improve hardening. Because of the low chromium levels in 52100 steel, it has very low corrosion resistance compared to other higher chromium tool steels.

In applications where corrosion is less of an issue, 52100 tool steel is considered an ideal, affordable option, offering a very fine grain with superior edge retention. It is capable of cutting a wide range of materials because of its combination of toughness, wear-resistance, and hardness.”
According to Carolina Knife Company.

(Thanks Brian for the head up !)