Shitaji: Ground Layers
Once the substrate is stabilized and reinforced, the shitaji (ground) is built up in progressively finer coats — the structural foundation everything else sits on. Wajima's version, ji-nuri, is a three-pass sequence:
| Pass | Name | Mix |
|---|---|---|
| 1 | Ippen-jizuke | Raw lacquer + rice glue + coarser earth powder (jinoko) |
| 2 | Nihen-jizuke | Same components, less rice glue, finer earth powder |
| 3 | Sanpen-jizuke | Least rice glue, finest earth powder — for adhesion and hardness |
Each pass is dry-polished flat before the next goes on. Wajima's signature material here is jinoko — a diatomaceous earth unique to the region, whose microscopic pores let lacquer penetrate the particle itself rather than just coat it, which is a large part of why Wajima-nuri has a reputation for exceptional durability. (Japan Artisan Foundation)
Grade tiers you'll see referenced elsewhere
Conservation literature on Japanese lacquer generally describes a hierarchy of ground recipes by cost/quality, useful for recognizing what you're looking at (or buying):
| Tier | Recipe |
|---|---|
| Premium | Fairly pure urushi + tonoko (powdered earthenware) → sabi, a grey paste |
| Mid | Nikawa — animal glue based, reddish-brown, cheaper |
| Economy | Rice paste + powdered earthenware |
| Modern/cheapest | PVC-based ground (not traditional, conservation-flagged as lowest grade) |