It’s been a while since my last post, but nothing really interesting has happened during that time. About a month ago we started making 5 new katanas and now they’re almost finished, only handles need to be wrapped and sheaths to be made.
During past few weeks I’ve researched about steel bluing processes – both hot and cold bluing. During this research I bought sodium hydroxide, potassium nitrate, hydrochloric and nitric acid. And finally about a week ago I found out how to get really nice black mirror like finish. It’s actually quite simple – melt pure sodium hydroxide (it melts at 318°C) and heat it to about 500°C (until stainless steel pot is red-hot and glows magically) and put the metal piece in it. Keep it there couple of minutes so it reaches the same temperature as NaOH and viola, it’s done. This process creates really strong oxide layer on the metal, so it should prevent rusting and make it stronger overall. Time will show if this is really so. And by the way, if 500°C sodium hydroxide splashes to your skin, this isn’t the most comfortable thing in the world. Kids, don’t try this at home.
Here’s little overview how the process looks like in our shop.
Hand guards (tsubas) are waiting to be blued.
Hot bluing process close-up.
Tsubas are drying/cooling after bluing. Here the left one had to be redone, because for some reason it had brown oxide, not the needed black.
Polishing guards. Here is half polished tsuba, I think you can see the difference of before and after polish.
And this is how it looks already mounted on sword (it’s our older style sheath, with bronze rings, new ones are with brass and look much better).
And here are the new swords that are finished real soon now.
Little close-up of rings and details, as you can see all details are not yet polished, but those which are look real nice.