Hello!
We would like to express appreciation for visiting blog of Asama hot spring “Nisikinoyu Jimotoya”.
On February 8th, TV program of NHK(Japan broadcasting corporation) showed National treasure “Himeji castle” repairing project as “Project X(Shirasagi castle recovery)”.
Once a 50 years, Himeji castle has been repaired on a large scale. Specific technique is repainted by white plaster(shikkui) of roof tiles. Black mold discolored roof tiles white plaster.
In Himeji castle, only one special technique (white plaster with haigashira:haigashira tuki meji sikkui) has used. This technique is not used by the other castles in Japan.
White plaster of all 75 thousand roof tiles were repainted. This is reason(secret) of white of Himeji castle.
below is roof tiles and covering plaster

below is plaster(haigashira) repaint techinique by special trowel
Next, on the contrary we show the reason(secret) of Black Matsumoto castle. Matsumoto castle was constructed on AC 1594 and is the oldest original castle donjon tower in Japan.
For beauty, National treasure “Matsumoto castle” also has been repainted by specific black lacquer (Kurourushi) in every Autum(from approximately September to October).
Repaint is conducted for wooden made black portion of water proofing purpose(on black wall portion:shitami itabari or hahu etc)
Black lacquer painted castle is only Matsumoto castle in Japan. India ink mixed with persimmon tannin is applied as plymer on wooden board. After that lacquer with black iron content is painted above.(this means black color lacquer: this is called kurourusi)
Below is Kurourusi(black lacquer)
Lacquer film on board is weak against ultra violet lay because Matsumoto city is located at high altitude 600m from sea level. Every year, local area lacquerers has painted matumoto castle.
Repaint period varies due to temperature or humidity of season. New lacquer is hardened by appropriate humidity and become beautiful. This is reason(secret) of Black Matsumoto castle.

Below is black chidori hafu board painted.
Would you like to visit National treasure Matsumoto castle colored by black beauty?
Matumoto castle live broadcasting URL:
https://www.youtube.com/watch?v=_XeAVwJqNnU
Matumoto castle english URL:
https://www.matsumoto-castle.jp/eng