Niage is a common and basic Japanese patina for copper and copper alloys such as shakudo and shibuichi that has been used for centuries and is also referred to as a rokusho patina.
Depending on the formula and soaking time, many colors can be achieved with this patina. On copper you can expect to see anywhere from a light tan/orange to very deep red tones while rokusho on shakudo can result in dark grey to black or even deep purple tones, and on shibuichi it will turn it a light to dark grey.
There are many variations to the basic formula and method and every artist tends to have their preferred way so while this might not be the way you would choose to do it, this is the way I’ve become accustomed to and like the best.
Play around with the ingredient proportions and soak time to find your favorite.
Just a word on caution, whenever working with chemicals, vapors, dust, and heat be sure to take any necessary safety precautions when using or disposing of these ingredients. Be sure to use proper ventilation and or respirators, gloves, and any other skin protection you might need. Please research how to safely handle these ingredients and what effects they might have on you and what your local laws concerning disposal might be. I take no responsibility for any issues you might have regarding this tutorial so please research safety information before attempting. You can also look through the Occupational Safety & Health Administration website for more info regarding safety and regulations.
What you will need
The main ingredient in a typical niage patina formula is Rokusho which is a mixture of chemicals such as copper acetate, copper sulfate, sodium hydroxide, calcium carbonate and other ingredients depending on the particular formula. I use a premixed Rokusho formula available at some metal sculpting and art supply shops.
It is granulated and green in color.
Another important ingredient is cupric sulfate which comes in bright blue crystals and is used to develop the patina color.
Many people use a Daikon radish and swear it enhances the coloring process even though I don’t know exactly how. It smells kind of pungent but I still use it.
You will need a bowl or pot to brew the ingredients and soak the pieces in and you can use glass, ceramic, or copper.
I picked up a small copper bowl for a good price and it works well for me. If using copper, make sure there are no steel screws/rivets that will be immersed in the solution as this can affect the results. The vessel works best when seasoned and this will happen naturally after a couple of uses but you can run a batch in it without adding your objects if you wish to prep it.
Another optional item is a copper mesh basket. I use this when there is an object that I can’t run a wire through, but for seppa and habaki I usually use some pure copper wire and a chopstick to suspend the pieces in the bath.
A plastic mesh basket can also be used.
Respirator, mask, eye protection, skin protection
Use distilled or purified water instead of tap water.
Step 1 – Cleaning the pieces
For this tutorial I will be using three sets of copper seppa I made.
Perhaps one of the most important things you can do to ensure a successful patina is to make sure the objects are as clean as possible. The level of polish can make a difference in the clarity of the color and sheen but you must make sure there is no dirt or oil or any other foreign matter on the piece at all. I usually give a couple of swipes with a file to achieve a surface texture on seppa but this also helps remove any dirt on the surface. You can also use soap or acetone but always rinse thoroughly afterward.
I finish up with a good scrubbing using a magaki-bake and 800 grit silicone powder in a slurry and then rinsing off with water. A standard scrub brush and cleansing powder can also be used.
After you finish cleaning the pieces, avoid touching them with your bare hands from that point on.
Step 2 – Prep soak
I like to soak the pieces in distilled water and Daikon radish anywhere from 5-30 minutes before I start the patina. I first prep the radish by thinly slicing about half of it while shredding some as well.
I add the slices to the bath while the shredded portion goes in the soak.
I also rub the clean pieces with some of the radish
Then I add them to a bowl with enough distilled water to cover them. I also squeeze in some daikon juice.
Step 3 – Prepping the bath
While the pieces are soaking with the radish in water I start measuring out the ingredients for the bath.
3.5 grams of Rokusho salts. An alternative proportion for copper is 4 grams of Rokusho.
5 grams of cupric sulfate. An alternative proportion for copper is 3.5 grams of cupric sulfate.
1-2 pints of distilled water. More water can be added as need if the level decreases but make sure it’s heated before adding to maintain the brewing temp. The exact amount of water is apparently not very important, just make sure it’s enough to fully immerse your pieces in.
Heat the water in the pot on a low heat and slowly stir in the Rokusho. Make sure you have proper ventilation and don’t breathe in any vapors, I use the built in stove fan/exhaust.
and cupric sulfate, stirring until completely dissolved.
Once the brew has reached a light simmer, throw in the sliced Daikon.
I then let this cook for about 20-30 minutes before adding the pieces.
Step 4 – Add the pieces
I feed a thin copper wire through the hole and hang the seppa from a wooden chopstick resting on the edge of the pot which will suspend them in the liquid.
I let them brew for 15 to 45 minutes or longer depending on the desired color, I have read that a very deep red was achieved on copper in a session more than 10 hours. I wanted a burnt orange/reddish brown this time so I let it go for approximately 30 minutes. I occasionally stir the mixture with a plastic knife, just make sure it’s not something that can contaminate the brew.
You can check the progression as often as you wish. Be sure not to let the pieces stay out of the liquid for too long while viewing them.
Step 5 – Rinsing
When you’ve achieved the color you desire, promptly remove the pieces from the brew and immediately rinse them in warm water, be sure not to let the solution dry on the surface. I set a bowl of warm water on the side and then just transfer the stick with the hanging pieces right over to the bowl.
Gently wipe the residue off of the pieces and then pat dry with a towel. Be gentle with them as this is not a super durable patina and is not meant for heavy use items. While they are still warm, I quickly apply a thin coat of microcrystaline wax and buff to a nice sheen. You could give them a coat of clear lacquer or just leave them with nothing at all, it’s really just personal preference.
Make sure to dispose of the waste properly, check your local laws and regulations regarding this.
This is a pretty fool proof patina as long as you follow the directions and above all, make sure the pieces are clean and nothing contaminates your bath.
Good luck and have fun!
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