There are many types of metal that are used in kintsugi. This post will talk about the most common grind which is a fine powder and is called keshifun or keshi in Japanese.
This is what is mostly seen in pieces that are done with real kintsugi and have real gold or silver applied to them. It doesn’t need to be polished but it will take a burnishing if you want to. It is more durable if it is polished but that also makes it shinier. I prefer it matte so I usually don’t polish it. It also doesn’t need an overcoat of lacquer.
There are several types of lacquer you use in kintsugi. I will go through each of them and this post is on the basic lacquer called kiurushi. Kiurushi is used in most of the basic steps of kintsugi. For sticking pieces back together you mix it with flour or rice, to do fill work or to do restorations you use it and mix it with either jinoko or tonoko to make a mixture called sabi. If you are doing a repair such as fixing a blistered glaze you would use this lacquer too. I don’t use wood powder but if you did you would mix it with kiurushi. It comes out of the tube a brown milky color and as it drys it turns black or a very dark brown. It can cause skin rashes but doesn’t seem to do so with everyone. I get rashes but most of the people I have had in workshops have never gotten a rash despite having direct contact with it. Like all real lacquers it requires a damp and warm environment to dry properly, it won’t usually cure in a normal environment.
There are several steps in kintsugi where you need to either sand down or polish parts of the piece.
The initial use of sanding is after you have either stuck the pieces back together or done any kind of work wherein you have to smooth the seam. You can use either sand paper or specialized whetstone type materials.
Soft whetstones come in the following meshes, #400, #600, #800, #1000, #1500, #2000, #3000.
There is almost no difference between the different meshes as far as appearance goes so I will just put this one photo up.
I use the meshes #400-#600-#800 to do only the roughest work on the seams. I never use them on graded metals as they are too rough and will destroy the metal. If you use any of the soft whetstones on unglazed ceramic or directly on rough sabi you will wear them right out and have very little effect. You should use the rougher meshes to smooth out sabi but don’t expect them to last if the surface is very hard and rough.
I use the meshes #1000-#1500 to do the initial polishing of graded metals. Use #1000 delicately since it can rip the metal off the lacquer. The #1500 will shine graded metal to your final state. After that you need to use #2000-#3000 to polish away the scratches from the #1500 and get to almost your final shine.
Note that polishing metal is only for graded metal, not for fine powder. If you polish fine metal it will come right off and you will ruin it.
There are 2 types of powdered, clay type materials used in kintsugi. Jinoko is a powder and is a rougher grain. Tonoko is a mass and is a finer grain. Tonoko has to be smashed to be used. The material itself is a finer mesh than jinoko although it looks like it is rougher since it comes in rock-like masses.
You use tonoko for making a mix called abura tonoko which is used for polishing graded metals. Graded metals are the rougher grades that start at #1 and go to #15. You don’t use tonoko for polishing the fine gold powder. You also use tonoko for making a mix called sabi which is used to do restoration work. It is mixed with water first and then lacquer.
There are many ‘recipes’ for sabi. I don’t use any types of set proportions but I have seen 2/tonoko to 1/water to 1/lacquer.
You use jinoko to make your sabi stiffer if you like. That is, if you are doing restoration work you can add jinoko to the mix and since it is rougher it will be a stronger mix although it will also be rougher since jinoko is rougher than tonoko.
Here is a series of photos of bowls I am repairing. The problem is the glaze blistered in the wood firing.
The photo above shows the first application of jinoko and lacquer in order to help build a smoother surface.
The photo above shows the bowl with jinoko and lacquer after the blistered glaze has been sanded off.
The photo above shows jinoko and lacquer mix on the bowl.
The photo above shows one of the bowls before I did anything to it.
In order to get a defined line to sand you can draw a line that marks your outer edge of the sanding surface.
After this marking and before applying the jinoko and lacquer you need to sand the blisters down to make a smooth surface. It doesn’t have to be completly smooth as lacquer adheres better to a dimpled surface.
I sometimes get questions about polishing gold and why I don’t use an agate stone polisher.
Here are some photos of pieces with either powdered or numbered gold that has been polished or not with an agate tool.
The photo above shows #3 grind gold that has been ‘hardened'(see link http://www.kintugi.com/?page_id=225 , steps 1-4) Using an agate tool does do some smoothing. You can get a better finish if you use polishing stones. After using agate I suggest finishing it with the regular powders and lacquers outlined here, http://www.kintugi.com/?page_id=225 from about step 5.
The photo at the bottom of this series shows the same piece after it has been smoothed some.
The photo above shows keshifun, fine powdered gold, with a small spot polished with agate. This is one way to finish keshi if you feel it is necessary. It is possible to ‘tamp’ it down with agate. It changes the nature of the appearance of the gold and makes it more ‘gold’ like. I prefer for keshifun to have the unpolished finish which is why I don’t use agate.
The photo above shows the bottom of a very old Imari piece that is finished with keshifun and then parts of it have been polished and others not. I prefer the more subdued look of the unpolished gold.
The photo above is the same bowl as in the first photo after it has had a small area polished with agate.
The photo above shows #3 grind gold that has been ‘hardened'(see link http://www.kintugi.com/?page_id=225 , steps 1-4) with the entire line polised using agate. The cup is an antique that someone glued back together with a modern epoxy and I have done the best I can to smooth that and apply lacquer and gold over it but some of the epoxy is still visible. Using an agate tool does do some smoothing but it is not easy to see in the photos. You can get a better finish if you use polishing stones. After using agate I suggest finishing it with the regular powders and lacquers outlined here, http://www.kintugi.com/?page_id=225 from about step 5.
Here is a video showing polishing of fine gold powder.
There is no audio on this video. It shows the first step in using kintsugi techniques to repair blistered glaze. Sanding the glaze down to as smooth as you can get it is important. This bowl will be finished with either lacquer or a metal finish.
This video has no audio. It shows the first application of lacquer to a ceramic bowl that had bad blistering because of placement in a wood fueled kiln. I first used a grinder to knock off the blistered glaze and make the surface somewhat smooth. I will finish the piece with a gold or silver finish using kintsugi techniques.