Painting urushi lacquer
This step comes after filling cracks (Mugi-Urushi) but before applying gold powder. I call this step Painting as a translation of 塗りの研ぎ (painting and sharpening) from the Tokyu Hands tutorial. Since it’s up to you how many undercoats, middle coats, and topcoats you want to apply, I thought it was simplest to simply explain this step as what it is—painting with a brush.
The most complex process I’ve seen involves an undercoat of 生漆 (raw urushi), a middle coat of 黒色漆 (black urushi), and a top coat of red urushi. Notably, this process only appeared on an English tutorial1. All the Japanese tutorials I’ve seen skip the undercoat, jumping straight to black urushi after(the one with tonoko powder). From my own experience applying raw urushi as an undercoat, it almost entirely came off during sanding, so I didn’t see the point of adding an extra undercoat.
One artisan based in Ishikawa Prefecture2 suggests adding colored urushi corresponding with the powder you’re planning to apply. For example, yellow urushi for gold powder, and white urushi for silver powder. This makes a lot of sense. It made me wonder why black and red lacquer are still popular with DIY kintsugi today.
With use, the red lacquer will wear down, exposing black lacquer beneath. If you want to create this effect, you’ll need to mix iron oxide with raw urushi or buy kuro urushi pre-made. Many tutorials skip the black lacquer entirely and start with red. One tutorial even applies red lacquer first, then black lacquer as a finishing coat3 for silver powder. It seems fine to apply whatever lacquer you have for an undercoat, then a final coat for powder adhesion4.
Red lacquer is way thicker and more opaque than raw lacquer, so it’ll cover up all the tonoko and flour mixed in the previous steps. However, by mixing and oxidizing your raw urushi5, the thickness and opacity can be increased, so that’s worth a try. Messing with pigments and urushi mixes sounds like a promising experiment in the future.
Precision is key! To trace the same delicate crack over and over, you need a thin brush, a steady hand, and lots of patience.
Any brush will do, so long as it’s thin enough. For hairline cracks, paint a little wider than the crack so that the lacquer will adhere through use. Remember to let the layers cure and add several layers of red urushi to seal the line.
Don’t apply thick layers! Wipe excess off the brush each time. See Common Mistakes in Kintsugi 101 for example of what happens when you apply thick layers.
If you make mistakes, I’ve found that a low grit sandpaper soaked in water can remove partially cured brush strokes. There’s always acetone as well.
Be careful not to sand too hard! I scraped the porcelain glaze on the white teacup by doing this.
Rotate the brush to create fine circles or arcs
Fine line technique - remove excess first, use a fine sable brush, hold as close as possible to the brush tip. The smoother the surface, the crisper the line.
Liner brush requires watery consistency, hold brush perpendicular to surface with very little pressure, but urushi is thick?? I haven’t tried this yet but I’m concerned about the viscosity.
Really good red brush technique for a chip at 19:00 of this Urushi Central video.
Some people use sandpaper, some people use a whetstone, some people even use a variety of polishing stones. You’ll want to think about the scratches that will be left on the surface and use less abrasive polishing methods when you get to the final coat.
This fountain pen video uses vegetable oil & tonoko as a final polish for mild abrasion. Nice!
Kintsugi Oxford (EN) ↩
Kintunagi (JP) ↩
Kintsugi Library Youtube (JP) ↩
Tokyu Hands (JP) ↩
Let’s Kintsugi Youtube (JP/EN) ↩