File the crack with a diamond hand drill bit by hand
​to remove glaze around the crack.

Apply diluted Ki-Urushi (about 50/50 with turpentine).
If it's a narrow crack, 
​draw dots on top of the line where the pieces meet.​ 
After, place in a humid box for a few hours to a half day.

After a few hours, clean off the excess urushi.
Whilst cleaning, check if every big of the crack is stained by Urushi.
In some cases, dots might disappear
​when they go into the crack, if so, don't worry.

Clean excess urushi well, and keep in the humid box for a week.
If the line is fat,
you might need to repeat this process a few times
before you apply Sabi or putty.

Unfortunate cases
After the second attempt, some cracks will still leak.
If so, seal once more, and apply Sabi anyway.
​Then seal with Ki-Urushi again.