Polish to show hardening line.

[Charlotte]

I picked up a differentially clay masked bowie a couple of years ago at a blacksmithing club's auction.  The blade was sold as a demonstration piece by a master knife maker but largely unfinished beyond sanding enough to show the hardening line after the heat treat.

I thought I might finish the knife for the next time I visit the club. The question is: What is likely to be the best sequence of grits, materials, and techniques to bring out hardening line when polishing the blade?  The line is clear but rather faint at present.

 

[Charlotte]

Btw  I know that the hardening line is often referred to as Hamon  ,   I don't think that term is appropriate for all differentially hardened blades.  When I see it on blades that are not done with the care needed to make  fine weapons I feel as sense confusion.  The blade I mentioned in the first post is, I believe, forged from O1 alloy for demonstration purposes.

Just my personal prejudice speaking.  

[Frosty]

Hamon is the commonly accepted term for the line between the edge and body caused by differential hardening. Of course it's appropriateness is the opinion of this non-bladesmith guy and I'll happily accept correction from any one, or the consensus of the world class bladesmiths that hang out here.

Frosty The Lucky.

[rhitee93]

There are a couple of major schools of thought on this.  Most non-Japanese methods involve carefully polishing the blade up to very high grits. I go to 2500.  Then using variations of acids to add contrast between the different steel structures.  Good polishing techniques are a must, but I will let you find a better reference than me on those.  One quick pointer, however, is not to let a buffer anywhere near your blade.  The polishing must be done with open abrasives a buffer will blur the line.

The Japanese method uses a variety of water stones to bring the blade to a high level of polish.  Conventional "Internet wisdom" would have to believe that the use of these stones as opposed to synthetic abrasives causes the hamon to pop out all on its own without etching.  This is a bit misleading.  If you read sword polishing texts, you will find that Japanese artists do not use acid as an etchant, but do use different abrasives above or below the hardening line to accent the different steel as well as materials that tend to darken one steel structure more than the other.

Edited July 20, 2015 by rhitee93

[Steve Sells]

Also be aware the Traditional method leaves an open grain, whereas Modern power tools roll over the grain smearing the finish.

[Charlotte]

Thank you for the informative replies.  It gives me a direction to go in with my collection of assorted stones.  The question occurs to me is what grit level would hard black Arkansas stone be considered?  I have several that I use for sharpening wood working chisels.  I could alternate the sides with some oil stones that I used years ago for polishing a plastics die mold.

 

Thanks Again for the response

 

 

[jmccustomknives]

Japanese wet stones worked differently than an Arkansas stone.  The Japanese stones worked more like a polishing paste, as the grit released in the water it formed a mud and this is where the polishing action takes place.  You can use wet/dry sandpaper from an auto parts store.  Depending on the size of the blade and how fine the starting polish is will determine the amount of paper you'll go through. 

[Charlotte]

Japanese wet stones worked differently than an Arkansas stone.  The Japanese stones worked more like a polishing paste, as the grit released in the water it formed a mud and this is where the polishing action takes place.  You can use wet/dry sandpaper from an auto parts store.  Depending on the size of the blade and how fine the starting polish is will determine the amount of paper you'll go through. 

Thank you for the reminder.  I had forgotten that part of the Japanese wet stones. I guess I'll go with the wet dry as this is a donation project in the end. Rather spend the money on NS fitting use the rose wood scales I bought a while back.