20CV Rust Pits :(

[Obsessed with Edges]

^That blemish doesn't look like rust itself, but maybe some pitting (etching) left by something else that came in contact with the steel. OR, it may be something hard that rubbed against it, leaving a burnished spot behind. Either way, it looks like the surface finish of the steel has been altered, one way or the other. BKF won't help with that. Sanding the blade likely would even out the finish. Easier solution: just live with it as it is.

 

[Obsessed with Edges]

Well, I live in Brazil, so I’ll have to import the BKF, but looking at eBay there was 2 kinds:
And sorry, it wasn’t written on blue stick. Actually is red stick shape at top. (...)

Wouldn't surprise me if those are the same product as we use here; maybe just labelled or packaged differently for different regions or countries. You might look for the active ingredient listings in product descriptions. If it's got the oxalic acid in it, and in powder form, it may very well be the same stuff.

 

[Rhodies]

^That blemish doesn't look like rust itself, but maybe some pitting (etching) left by something else that came in contact with the steel. OR, it may be something hard that rubbed against it, leaving a burnished spot behind. Either way, it looks like the surface finish of the steel has been altered, one way or the other. BKF won't help with that. Sanding the blade likely would even out the finish. Easier solution: just live with it as it is.

I am leaning towards your latter suggestion...

 

[brasileiro]

Just to give a feedback... BKF arrive at home today and OMG!!! It really works.
Before, even dipped in water:

After 10 sec of application with very little amount:

Thanks for the tip!

 

[Sonnydaze]

Just to add that BKF powder, mixed with water to a paste, is a wonderful way to clean up your SIC hones after using them on sharpening systems, such as the Apex Pro or Wicked Edge. I was amazed at how quickly it works.

 

[Obsessed with Edges]

Just to add that BKF powder, mixed with water to a paste, is a wonderful way to clean up your SIC hones after using them on sharpening systems, such as the Apex Pro or Wicked Edge. I was amazed at how quickly it works.

I recently used it this^ way, on a SiC bench stone that I'd previously used with water and cleaned with dish soap & water and an old toothbrush. After that use and cleaning, when the stone was dry, I could actually see it was still clogged somewhat with swarf. Scrubbing it again with BKF and some water cured that. Clean as new.

 

[maximus83]

I recently used it this^ way, on a SiC bench stone that I'd previously used with water and cleaned with dish soap & water and an old toothbrush. After that use and cleaning, when the stone was dry, I could actually see it was still clogged somewhat with swarf. Scrubbing it again with BKF and some water cured that. Clean as new.

David I've been using this too for cleaning, for like the last couple years, and it has been great for that. In fact this is my primary usage of BKF other than cleaning cooking pans, I use it to clean all AlOX, SiC, Spyderco ceramic, and diamond stones/plates. With my stone types I listed, I can generally rinse off with water or a little Dawn detergent added, and scrub lightly with an old toothbrush. When there are stubborn deposits or a lot of swarf from doing a profile or working a primary grind, I use BKF with a scotch green pad, it really makes the difference on all these stone types. It has notably reduced the case like with my AlOx stones where you can get swarf embedded down deeply in the stone surface, then it 'rusts' and causes discoloration of the stone, which is admittedly only a cosmetic issue, but it bugs my OCD nature for some reason. BKF is the best thing I've found for deep cleaning sharpening stones.