I will start by saying that in polishing a blade there is not one process that fits all. Over years of practice you develop a technique that works for you and for the kind of steel that you use. You change your polishing techniques according to what you want the final effect to be. In this particular case I am venturing into new territory. I am using a kind of steel that I have not polished before and quite likely I will be faced with different dilemmas along the way. In general I would say that when polishing Japanese style blades or any blade for which you intend to display a hamon, there are two general ways to proceed: one is to use stones (whether synthetic or expensive natural ones) and go through the different stones according to a set sequence and the other is to use wet/dry sandpaper and progress along the different grits. What really changes everything is the final step in polishing, what the traditional Japanese polishers accomplish with the hazuya, jizuya stones and nugui. For the Western, non-traditional or hybrid polish or whatever you want to call it, this is usually a combination of a mild etchant (ferric, vinegar, lemon juice) followed by a cleaning of the oxides left by the acid with a paste polish (Pikal, simichrome, etc) and finally a bit more polishing with pumice or other compound mixed in oil or water and backed with cotton or leather. It is a process of trial and error that tends to be different for each blade.

I would show you first my simplistic setup. You can polish by moving the blade on a fixed stone or polishing board to which you would attach the sanding paper or you can keep the blade fixed and move the stone or the paper along the blade. I choose to use sandpaper and to keep the blade fixed. I use a piece of corian to back my paper and hold it by pinching the paper against the corian between my index and thumb fingers. That is what works for me. I get plenty of light coming from two light sources aimed at different angles on the blade and clamp the blade to a table near the edge with quick-grip vises.

I had finished the blade on the grinder with a 220 grit along the length of the blade.

Depending on how well the machined 220 grit looks I will start with either 180 or 220 grit paper. In this case I had an inspired day at the grinder so I can start with 220 grit paper. I will work at a 45 degree angle so that I can clearly see the scratches from the previous round. The goal is to evenly removed all of those scratches completely. This tanto is hira zukuri so I don’t need to worry about a shinogi line. The hand worked 220 looks quite different from the machined 220 as you can see.

Then I move to 400 grit paper and work at 90 degree angle from the previous marks. Again, there are many ways to do this and some people work first at 90 degree across the blade and progressively tilt the angle until at the very last steps they are only working along the blade. I prefer to alternate each paper at 90 degrees from each other and switch to working along the blade at the end.

Once I have finished with the 400 grit I will stop there and start working on the fittings (koshira). There will be some slight damage that may occur to the blade during the fabrication of the koshira and it is easier to erase those by redoing the 400 grit than having to redo all the steps if I took the blade to a final polish before doing the koshira. For these two blades I will make two copper habaki and a two shirasaya. Simple and elegant, I am not showcasing the koshira, I am putting the emphasis on the steel in this project. I will not detail the process of making the habaki. I have a separate tutorial on my webpage for that.

What I am going to do different is to apply a patina to these two habaki to take them up a notch. The patina is called niage and it is based on the Japanese rokusho patina with the addition of copper sulfate. Niage means to boil and I will immerse the habaki in a heated coffee mug with the solution for two hours depending on the desired color. Copper put to this process goes from yellow to brown to orange to red to dark brown. I will stop the patination at orange-red.

Here is the result.

I have made two shirasaya out of poplar and alder.

They will be coated with a few layers of clear lacquer.

And a sayagaki (inscription) will be printed on them  

Now I can proceed to 600 grit paper on the polish and work at 90 degree angle from the previous marks. 

Then 800 grit paper and work at 90 degree angle from the previous marks. 

Then I move to 1000 grit paper and switch to working along the length of the blade. The surface is becoming more mirror-like but no signs of a hamon yet. In other steels such as when I work with cable the hamon is obvious by this stage. By the way at this point I am adding some water to make a mud that acts as a lubricant and polishing paste of sorts. 

Then I move to 1500 grit paper and continue to work along the length of the blade but I have stacked a piece of leather between the paper and the corian and continue to use water as lubricant. As you can see in the pictures the hada has now become visible to the eye of the camera. 

Here is a picture of the polishing “tool”. Corian, leather and paper with the water slurry on the blade. 

I continue to use the same backing and move up to 2500 grit paper. The hada is visible but no hamon. Something had gone wrong. 

I would normally etch the blade at this point rather than using the hazuya and jizuya stones. I need to etch anyhow since I am worried that something did not work well during heat treatment. Here is my setup for this process. I have a swivel vise that allows me to flip the blade from one side to the other quickly and I will prepare a mixture of lemon juice, vinegar and soap to be heated up in my coffee mug. 

I use a cotton ball to first clean up the blade with Fantastic and then apply the hot etching solution. 

And here are the bad news. The hamon shows up as a very thin line along the edge. Talk about shallow hardening. Even that amount of edge was enough to withstand the usual cutting tests (wood chopping, hair shaving) with the edge holding just fine but it is not what I was expecting. 

A big disappointment indeed. But that is part of the learning process. I continue with my polishing as I want to figure out the steps to bring the hada out. At least I know I have a great hada there. Here is my bag of tricks for this. I first use a ceramic polishing compound that contains citric acid backed with a 3M polishing pad. I follow that with an automotive industry polishing paste backed on the same pad. Then I will use a clean sanding pad to clean up all the residues. I follow that with nugui (iron oxide) diluted in cutting oil. Then pumice backed with leather to clean up the residues. I will follow with 2500 grit paper with water first and then dry and then go back to the 3M soft sanding pad. This sequence is specific to these blades and I worked this one out through trial and error. Each blade depending on the steel they are made of and the kind of heat treatment tends to behave differently at this stage.

And these are the results: First the tanto with the itame hada. 3 pictures follow. 

Second the tanto with the ayasugi hada. 3 pictures follow.  

Beautiful steel.

A final picture.

It has been a fantastic journey and I appreciate everyone who has followed along. There is so much to learn…