Japanese Chisel

[Corset]

Due to a bit of excessive grinding to adjust the profile on a japanese chisel I have ground off the black effect on the metal. Has anybody any idea how it can be restored. Its not the end of the world but it does look a bit odd now and I know that shouldn't bother me but it does
Owen

 

[GazPal]

Black effect? Assuming this is where the smith/maker etches a blade after forging and polishing to check lamination consistancy, simply warm the blade gently and dip in warm citric acid or white vinegar. This should re-darken the harder steel within a few minutes and leave the softer steel paler. Hard edge steel and softer spine steel/iron etch at differing rates with varying effects depending on the steel used.

The same can be done to check the extent of lamination on older plane irons (e.g. Record "Best Crucible Steel" irons) and chisel blades.

 

[Corset]

I think it must be something like that however the softer iron is black and the harder steel is shiny. Although I suppose this could be polished again to be shiny see photo at bottom of link
http://www.woodworkersinstitute.com/print.asp?p=1249
When you say warm gently I presume you mean with a blow torch or alike and not a hair dryer?
Owen

 

[GazPal]

I think it must be something like that however the softer iron is black and the harder steel is shiny. Although I suppose this could be polished again to be shiny see photo at bottom of link
http://www.woodworkersinstitute.com/print.asp?p=1249
When you say warm gently I presume you mean with a blow torch or alike and not a hair dryer?
Owen

Warm gently as in hair dryer rather than risk drawing temper using a blow torch. :wink:

If the back steel is darkened while the harder edge steel is bright, it's probably a form of chemical bluing/blacking treatment (Read gun blue or gun black) that's been applied during production. I'd honestly just use the chisel/chisels as is and not bother re-bluing, because it'll wear back to clean steel each time you whet or re-grind the blade.

 

[LuptonM]

Wouldn't the black effect be from the carbon deposits from using a charcoal furnace

 

[GazPal]

Wouldn't the black effect be from the carbon deposits from using a charcoal furnace

Not if the steel is cleaned and sharpened properly afterwards.