Repairing my mug with Kintsugi
fellerts.no
fellerts.no
People opt for epoxy because Urushi lacquer is traditionally made from poison oak sap and is a potent skin irritant to most people (it's where urushiol gets its name). It's really tough to do Kintsugi without smearing trace amounts of it all over the place, especially if you're doing it with kids, and cleaning it off is a pain since it's a hydrophobic sap. Even trace amounts can cause a reaction, especially if someone has sensitive skin or is severely allergic. People who do a lot of kintsugi develop a tolerance for it but it's an annoyance that most hobbyists just don't need.
Epoxies can be perfectly food safe and the FDA has a database [1] although it's not particularly user friendly. You can get MAX CLR or similar from Amazon. I wouldn't use it in an oven above 300F but it's fine for boiling temps. These FDA approved two part epoxies are used all over the place in hospitals and food manufacturing facilities where they're used to coat rough surfaces that would otherwise harbor bacteria.
[1] https://www.cfsanappsexternal.fda.gov/scripts/fdcc/?set=Indi...
Depending on your goals though non-foodsafe epoxy can work well. Thickened marine epoxy, for under-the-waterline boat repairs is rock solid for decorative items. I'm sure it's toxic af and I wouldn't want it anywhere near my food but it would be fine for a lot of the things people want to do kintsugi for.
Cashew lacquer is also pretty cool. It's nowhere near as nasty as urushi and doesn't require a special environment for curing. If I were just getting into it now I'd probably start with that.
Hum... That can't be a coincidence. Both plants are on the same family. Let me check...
Yup, Cashew produces urushiol also. Unlike pistachos, cashew shells must be removed before selling the fruits for this reason.
So cashew plants can trigger skin allergies. Is a common family thing. Harvesting this things burn the workers hands. My bet is that would be also unsafe for people allergic to poison ivy.
I can't say I have any desire to try it myself.
Side-note: I did get some raw urushi on my fingers while working on this project, but nothing happened. Perhaps I'm immune.
Might also be enough mechanical rubbing on fingertips during normal use that it mostly scrubs off. Whenever I feel it coming on from Urushi or accidentally touching poison ivy in nature, I rub it with water and course sand/dirt which seems to get rid of the urushiol.
Urushi is more of a pain in the ass because its made from the sap, but Windsor and Newton artguard barrier cream seems to really help. Ideally apply it before use but it helps washing it off too if you forget.
Somewhat the opposite. To be immune to it, your immune system would likely have to tolerate the authentication failure this substance causes after binding to a cell…which could be Bad in many other ways.
A likely explanation is that you removed the substance before an immune response could be mounted.
Molecules of the contaminant bind to skin cells around 15 minutes after contact. The affected cells are disrupted only in that they can no longer provide the appropriate response when challenged by an immune cell. When a cell cannot be identified as a member of the host, a chemical signal is released which tells killer immune cells to congregate and kill everything in the area.
This attack mounted by the immune system is the source of the irritation. It can be mitigated by antihistamine (somewhat), lower temperatures (somewhat, espeically on the verge of shivering), steroid injection (strongly).
Note that recontamination is the most common cause of "spread". Only a single molecule is enough to cause a reaction. Contaminated clothing and surfaces can still bear the oil after multiple washings.
Tsuge is a good brand to search for if you want to see exanples. Cost-wise such pipes start around the two hundred US mark.
Is there any reason to believe that these epoxies won't just be like PFAS where in a few years the EPA/FDA will decide that they were actually risky?
https://www.wisebond.com/blogs/epoxy-blog/is-epoxy-food-safe
I've been doing traditional kintsugi for about twelve years, a couple hundred successful repairs. Though when I started there was very little instruction or english-language resources available. It's become pretty popular for obvious reasons which is great for people getting into it now.
It remains probably the most difficult and frustrating skill I've ever learned. It's really hard to communicate just how meticulous, near-impossible some of the joins can be. There is a huge variety of technique and nuance to learn about different media and lacquer ratios for different kinds of joins & fills and it all needs to be done by intuition and experience.
And then the medium has no holding power until the curing process is well underway. So you need a lot of creativity to come up with a scaffolding system, pretty much completely unique to each project. Any problem after applying lacquer means hours of careful filing and rework, and more days or weeks of curing.
An edge-of-my-skill repair on a complete shatter takes about 100 hours spread out over 2-3 months. Even just an ideal three piece clean break is easily 8-10 hours and a handful of weeks.
Are you entirely self-taught then, or did you find a mentor?
Early on I got most of my info from the newberry library. It had a collection of illustrations and manuals donated from a defunct lacquerworks museum in japan, for some reason. They had someone around who even helped with a lot of translation for free which was a major help. All this stuff is available and better explained on youtube now though.
A pair of good articulating arm clamps is my starting point for almost everything. I like to put the "main" piece directly under the shard that is being joined. You want the pieces as tight as you can get of course but you don't need a ton of pressure on there. The flour in the medium will draw it together some as it dries. If you get a good bond but it cures with gaps or holes in the join, you can fill in later with lacquer mixed with a fine clay. Tonoko or jinoko are the key words if you don't have it on hand.
Usually there's at least one join where you need to set multiple pieces at the same time. Sometimes I'll use a single string tied across the outermost shard to keep pressure on, usually across the rim of a bowl or cup. More than one string is too much to keep track of for me though. And the lacquer fumes are extremely detrimental to rubber and elastic, they will harden and break with a few hours of exposure so I don't use them at all.
A more traditional move is to bury the main body of the repair in a dish of sand, with the part to be joined exposed. Then arm clamps or whatever to hold the pieces together. Just make sure any joins that touch sand are fully cured. The cleaner you work the less sanding you'll have later. But there will always be some so do what's necessary to get it together then clean afterwards. I've even used masking tape to hold some many-pieced shatters together. It's a mess but it works, provided the piece doesn't have any texture or decorative elements that could be damaged by the sanding.
Good luck! It's the most tricky and frustrating part, and where most of the failures happen. You should probably expect some failures and setbacks, it's just part of it.
I got into Kintsugi when my toilet needed repair. It’s a rewarding craft https://thingsilearned.com/things/my-kintsugi-toilet/
No affiliation. I gifted my partner an intro workshop pass and she's been returning for more classes since then.
The guy running the workshop had us use epoxy and not urushi powder (not surprising; I'm sure all of us would have ended up with severe skin irritation otherwise). The article mentions concerns about food safety; IIRC we were told that the epoxy we were using in the workshop was not food safe, but that it's easy to acquire food-safe versions of it.
We also didn't do this in anywhere near as many steps, with as many different treatments for different sizes/shapes of damage. Ultimately we fully repaired a piece in a couple hours, not the several months that the article author took to do it right. (And the extra care and use of the proper materials shows; the final repaired alligator mug from the article looks orders of magnitude better than my work.)
That said, Urushi is great and the number of things you can do with it is truly amazing. Just don't do it rashly.
Most of the methods taught in the US are "gold relief" methods, which is basically glue with golden pigment mixed in. It doesn't look great but is modern and quick. "Gold flush" methods take a bit more time and are more authentic, but still don't use the traditional materials shown in this article.
Does anyone know where to get these traditional materials for use in classroom settings (i.e. in bulk, preferably discounted)? Not massive scale, just enough for a few classes. The kits have such a tiny amount and are so expensive, even a bulk discount of ~10-20% would be ideal.
Now I get new mugs when one breaks.
But OP’s process brings to mind the way we remember things: by reliving them in such a way that can (and usually does) produce a unique and slightly different product from the original. It’s the investment of time, thought, and love that makes this process more desirable.
I’m reminded of a recent comment thread on Jaloponik, where some great heads were talking about just _why_ the fact that anyone can go 0-60 in less than 4 seconds isn’t actually a great as it seemed to be. I’m a nutshell it came down to the fact that this used to be the product of untold hours spent learning and iterating to eke out tenths of a second, over time, to finally reach that level.
Admittedly it smacks of gatekeeping, but there is a fine line between gatekeeping and rewarding true mastery of an art.
This is a very advanced and difficult method of glass re-forming.
That being said, there are excellent, optically-clear, UV stable epoxies that are made for this problem. Hxtal is the go-to for most. https://www.lakesidepottery.com/HTML%20Text/Tips/Hxtal-NYL-i...
It is very thin, and will happily wick in and fill cracks. Often the join is completely invisible. The downside is that the cure time is on the order of 1-2 weeks. It does take a little practice to use effectively, and it's worth trying on less-important projects first, but it's straightforward enough that you can expect success if you follow the directions carefully.
As for the aesthetics. No matter what you do, you don't get a whole piece. It is broken and always will be. What you can do is to create something new that both has the beauty of the old and the care, beauty, whatever of continuing. I don't know how to explain this in logic, but there it is. I had quite a nice ceramic cup with charm that broke. I used black urushi which was not gaudy like gold leaf can be. I liked it even more than before.
Another option is silver leaf instead of gold depending on the glassware. And finally you can get really crazy. Rankaku is where you get little tiny pieces of quail egg shell and place it into the urushi. It is painstaking - to say the least- but the results can be beyond stunning. https://www.pinterest.com/pin/jean-dunand-18771942--55309901...
there are lots of bonding agents and epoxies out there that are not urushi based , actually food safe, and just as easily doused in gold dust, and completely compatible with prepared ceramics.
I will not fault anyone for not believing the certification, but I would personally want to see a more authoritative source than an undated ceramics FAQ. But this is just personal style! Being suspicious of regulatory thresholds is prudent.
(And this FAQ has me wanting to revisit my priors and research this a little more specifically, because its assertions are plausible, but need sources or explanations or dates, for cross-checking. Food-grade epoxy I believe in would be a handy thing to have exist; I do have some certified food grade epoxy in my garage that I haven’t used for anything yet and I’d dislike downgrading it to just “epoxy.”)
Not idiotic! I've saved more things than I've further damaged by doing this.
Not hypotheticals, either of those, and not me.
The kitchen looked like a scene from Kill Bill. Perfect blood spray in an arc across the wall.
This mate lived with me at the time. And he was a nurse. He came home from his shift about half an hour later and I told him, sorry man, but you’re driving me straight back to the hospital.
I’m lucky to still have total use of my right middle finger.
It gives the mug so much character, looks better than before, and for sure it will be a conversation starter!
Dishwasher you can. The repair is really two parts: the bond that holds it together and the gold dust that covers the lacquer. The join bond can handle the dishwasher. The gold layer needs touchup every few years anyway, but it will need it a lot more often if it goes through the dishwasher regularly. Gold is expensive.
There are some other ways of applying the gold that can hold up better, but they're less common.