Is this rust normal or should I be worried ?

[Bosco]

I have little knowledge when it’s come to rust. Is this considering normal for 800 years old Nakago ?. Should i do anything to prevent it spreading further ?. Correct me if I'm wrong but this is rust isn’t it ?

[nulldevice]

Technically its all rust. The darker rust is the more stable form Fe3O4 or Iron 2 Oxide whereas the red rust is Fe2O3 or Iron 3 Oxide which is the more volatile rust that we want to avoid. 

 

Darcy is a proponent of oiling the nakago to prevent further degradation (Yuhindo - Oil Your Nakago). On an o-suriage mumei blade like this, a light coat wouldn't be a bad idea. Just make sure to use separate tissues when applying oil to the nakago vs the blade so you don't get rust or dirt particles that scratch the polish on the blade. 

[Bosco]

1 hour ago, nulldevice said:

Technically its all rust. The darker rust is the more stable form Fe3O4 or Iron 2 Oxide whereas the red rust is Fe2O3 or Iron 3 Oxide which is the more volatile rust that we want to avoid. 

 

Darcy is a proponent of oiling the nakago to prevent further degradation (Yuhindo - Oil Your Nakago). On an o-suriage mumei blade like this, a light coat wouldn't be a bad idea. Just make sure to use separate tissues when applying oil to the nakago vs the blade so you don't get rust or dirt particles that scratch the polish on the blade. 

Thank you for your information, it’s really helpful for me to understand more on rust. I’m looking for some advice, dealer told me it’s an old polishing but generally in great condition. For the rust, will oil darken it ?. Dealer asked if I want to get professional remove the red dust, or I can do it myself with oil. What do you think ?

[drbvac]

As stated above Darcy Broadbank suggested ligh oiling of the Nakago - others say don't touch it as the darkening is a sign of age - I wouldn't bother having it removed and a light oil would prevent any further forming of the red rust and it should be fine

[Robert S]

I agree with oiling to stabilize the rust areas.  My technique has been to apply a heavy oiling, to get the oil down into the dips and any micro crevices, and then careful repeated dabbing (not rubbing!) with a tissue to remove most of the oil on the surface.