My Japanese cup broke... and it's a $25 cup, so I can either throw it away and spend another $25 buying a new one, or I can spend $100 on a kintsugi repair kit, mend my cup, and learn a new skill in the process. Let's go with kintsugi.
I broke my coffee cup...
Mind you, my "coffee cup" was actually a large Japanese earthenware beer mug that cost $25 rather than your run off the mill $2–$4 coffee cup, so... do I buy a new one? I can, I have a job, but it seems weird to throw something like that away.
Then I remembered something: kintsugi. A Japanese practice of glueing broken pottery back together with laquer, and then dusting the seams with precious metal powder. The result is a mended piece of pottery that both looks very pretty, and will simply live on instead of being thrown away.
So, off to the internet I went to watch some videos on how to perform this art (David Pike has been most instructional, and is almost as soothing as watching Fushimi Maki make a honkatajiwan) and then hit up Amazon to buy a kitsugi repair kit.
Sure, the kit is $100 and the cup is only $25, but I have at least one more cup that can stand with some mending if this turns out nicely, and then the proposition becomes far less odd.
Based on videos by David Pike, I decided against using the tonoko clay powder, which can clump, and instead used plain sifted flour.
Here's my mixture of flour and laquer, to act as seaming glue, mixed to a consistency of a thick paste (for reference it's only a little less thick than blue tack). It dries while you work with it, but thankfully it dries rather slowly. Also, this was about three times as much as I needed, so hurray for learning!
Once all the bits have been pasted and seated, it's pretty much 24 of no-touch time, other than after a few hours pushing the pieces around to get smooth seating.
Lacquer is funny in that you can't really speed up the curing process, so your piece needs to be held in place while it cures. In this case, that means liberal application of "fairly loose" elastic bands. The last thing you want is the elastic to pull your pieces into something warped, so during initial curing you basically want just enough tension to keep things together, rather than "compressed tightly"
It's surprising how much the urushi/flour paste likes to, foremost, stick to itself, rather than the smooth fracture lines. So applying it is pretty painstaking.
Easy, but painstaking and quite time consuming.
And the cup's upside down, to keep the pieces pressed into the cup properly. This will sit for about 12~24 hours before more work is done.
After having this sit for a few hours, the lacquer gets to be a gummy consistency, which allowed me to clean it up off a little, which in turn makes it easier to sand the seams smooth once everything's dried out properly (although that said, it can take about a week for lacquer to *fully* dry, so the initial 24 hour curing period is really more about "making it possible to work on the piece" rather than "letting it cure until it's done")
After curing for about 24 hours, we have a fascinating situation: the lacquer is "hard" enough to sand, but nowhere near done curing. So... let's sand it down and then not touch it for another 24 hours.
Sanding the outside is fairly straight forward. A hard plastic scraper for taking off the obvious crumbling along seams, followed by 600 grit wet sanding paper, cut in 1x2"bits, which is then used to smooth off the seams and clean up dirtied spots. One rule of thumb: use too much sand paper. Don't be frugal with that stuff, the moment it feels like it's not sanding anymore, move on to the next piece. You're not helping yourself by trying to be conservative in this step: use *all* the sand paper at your disposal. Buy more if you have to! =)
When I tried to sand the inside of the cup, it became clear that the lacquer had not set enough for me to do so, so I gingerly sanded what I could, and then wrapped the cup back up in elastic bands to keep pressure on all the joins...
The outside sanded quite well, actually.
At this point the lacquer's cured enough to take better elastic to hold everything together, and more weight on top to force the last lacquer into setting into as tight a bond as possible.
This got sat for 48 hours, giving it the "expected + 1 day" window to cure to a point where I can handle the piece without it feeling like fragments are still a little loose.
After sitting much longer, and upside down, and with much more pressure, a cleanup showed much nicer joins.
The handle didn't feel tight enough, so I gave it some tactical massively powerful elastic, as well as string. It worked reasonably well.
Recleaning the outside of the fragmented break actually came out almost done. It needed very little further sanding.
It still needed some, of course, but it was a very, very civilized affair.
The inside of the cup, however, is a different matter. I messed this up. Clearly. I started cleaning too soon, and I used too much cement. and it became a mess.
But I have a rotary tool.
So I took that to the inside of the cup with some sanding heads... see next photo
One rotary sanding later, and things look a little less blarg. I'm not "happy" with this, I really wish I could clean this up better but this cup has one major aspect that makes it near impossible:
The inside of the cup is actually has a coarse, almost porous finish, which makes beer keep micronucleating, meaning it'll always maintain a bit of a head.
That's pretty neat! But it also means it's virtually impossible to properly clean.
So, this will have to do. Tomorrow: turning those brown, brown seams into golden joins instead.
After doing all the recleaning and resanding, it seemed that the ear was, somehow, still a little loose. This frustrated me. A lot.
So I tore it off.
And then it turned out that, really, only the outer 2mm of lacquer had set, and everything else inside was still most definitely soft lacquer, and that would have never set properly.
So: I'll be gilding the cup itself tomorrow. And then the ear will be a separate operation.
It's time to add the 金 part of our kintsugi. Step one: fresh lacquer on the seams, so the gold dust will stick.
The application is basically a mix of dusting and rolling. I do not have the tools to even attempt the kind of dusting stick technique that comes with "proper" kintsugi. This works.
It's a bit messy on the first go, though.