TLDW #6 - Natural Urushi Lacquer Base for Aikuchi Tanto Koshirae

**WARNING: This is the longer process version intended for serious students of knifemaking. Watch the overview edit here: https://youtu.be/09S76DSbbI8

Preparing the wood surface and natural urushi lacquer base for a traditional style aikuchi tanto.

Urushi is traditional Japanese lacquer made from the sap of a specific tree. The natural colour is a milky brown that oxidizes to deep chocolate and the black colour is created through a reaction with red iron oxide.

A note about the urushi techniques in the video: I make no claim to any skill in this area and my work is fairly rustic as far as lacquer quality goes. If you want to learn proper technique, watch everything ever uploaded to Fushimi~san's channel: https://www.youtube.com/user/fushimiurushikobo.

The lighting was not optimal for several of the steps here and several of the finishing layers are missing from the video, but the final stages are similar to the ones shown. The full process spanned a month and a half including curing and drying time in between each step. Each layer is allowed to cure in a warm, humid box for two to three days and then polished with charcoal and water before the next is applied.

The charcoal used for sanding/polishing was a sturdy piece made from a soft-medium density hardwood such as Nootka Cypress or Alder, the traditional choice being something in the density range of honoki (Japanese Magnolia). The charcoal can be shaped to the contours of the piece while working.

0:08 carved wooden handle and scabbard

Sealing
0:12 mixing sokui, water, and ki-urushi to make nori-urushi
4:11 using nori-urushi as an adhesive for the wooden fittings
(not shown: wiping the surface with ki-urushi or nori-urushi to seal it)

Filling the Base
6:13 mixing tonoko (~diatomaceous earth) and ki-urushi to make sabi
8:07 filling gaps and openings with sabi

Polishing the Base
9:58 leveling the surface with charcoal

Building the Mid Layers
12:56 brush coating with black urushi

Polishing
15:48 leveling the surface with charcoal

Repeat
17:20 brush coating with black urushi...and repeat to build up base...
19:11 finished work

Carving the Koshirae
https://youtu.be/kh0Scz7jiz0
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See the whole process of making this tanto: http://islandblacksmith.ca/process/making-aikuchi-tanto-kuro-urushi-koshirae/