Defect Diagnosis Table
Symptom-first, drawing primarily on Tamenuri Studio's diagnostic ordering from Chapter 21 (RH → temperature → oxygen → urushi condition → film thickness), plus general finishing-defect knowledge flagged separately where it's not urushi-specific.
| Symptom | Likely cause | Fix |
|---|---|---|
| Surface still tacky after 24+ hours | Humidity too low, or urushi/laccase activity has degraded (old stock, poor storage) | Check and raise RH toward 70–85% first; if that doesn't resolve it within a normal cycle, suspect the urushi itself (see Ch. 8 on storage) and test a fresh batch |
| Wrinkled, alligatored surface texture | Cured too hot, or applied too thick — surface "snap-set" while the layer underneath stayed soft | Lower cure temperature toward 20–25°C; apply thinner coats; let each fully set before recoating (Ch. 21) |
| Cloudy, hazy, or blushed patches | Condensation formed on the surface from a humidity/temperature swing during cure | Stabilize the curing box against ambient temperature swings; avoid opening the box repeatedly during a cure cycle |
| Small circular craters or crawling ("fisheye") | Contamination on the substrate — oil, silicone, wax, or skin oils from bare-hand contact — repelling the lacquer as it's applied. (This is general film-finish behavior, not urushi-specific — flagged as adapted general knowledge, not a source found written about urushi directly.) | Clean the surface thoroughly with a urushi-safe solvent before coating; always wear gloves per Ch. 2, which also removes this risk at the source |
| Coat won't cure at all, stays liquid/gummy for days | Sealed curing box with no air exchange, starving the laccase reaction of oxygen — or RH far outside range | Add small (~5mm) vents to the curing box; recheck RH against the 70–85% target (Ch. 4, Ch. 21) |
| Grit or specks embedded in a pigmented coat | Pigment not filtered before application | Always strain pigmented urushi through yoshino-gami paper before use (Ch. 3) |
| Kokuso/sabi filler stayed soft or spongy inside | Applied too thick in one pass, trapping air and moisture inside | Rework in 0.5–1mm passes with a full overnight cure between each (Ch. 13) |
| Warping or cracking at a joint or rim | Insufficient moisture stabilization or missing cloth reinforcement at a stress point | Address at the substrate stage next time — kiji-gatame saturation (Ch. 12) and nunokise at joints/rims (Ch. 14) are prevention, not repair; existing cracks need kokuso fill |