Seeking identification of an old Nanbu Tetsubin – possible Seieidō cast (Meiji–Taishō era)

[JackDo]

Hello everyone,
I’m looking for help identifying this old Nanbu Tetsubin (Japanese cast iron kettle) that I recently obtained.

Here are the main details I’ve observed:

Material: Pure cast iron (non-enameled interior).

Casting style: Sand-cast, entirely handmade.

Handle:

– Removable handle (可動弦 / kadōzuru) type.
– The handle is forged iron, attached through small pivoting rings on each shoulder.
– Surface shows hammer marks, suggesting hand-forging rather than casting.

Surface pattern:
– Full-body kiku-mon (chrysanthemum pattern), hand-stamped and overlapping.
– Subtle irregularities suggest pre-industrial stamping methods.

Seal / Signature:
– Vertical inscription on the side, appears to read 「南部盛榮堂造」 (Nanbu Seieidō zō) — though slightly worn.
– Relief casting, not engraved post-production.

Base:
– Flat base with natural casting texture.
– No vent holes or polishing marks, consistent with late 19th–early 20th century craftsmanship.

Estimated period: Late Meiji to early Taishō (circa 1890–1920).
Origin: Possibly from Morioka, Iwate Prefecture.

I’d appreciate any insights about:

Whether this seal truly corresponds to Seieidō or a related workshop.

The approximate period and type of casting mold.

Any advice for conservation (I’m currently seasoning it with strong tea infusion to stabilize patina).

Photos included: side seal, lid knob, handle joint, and base.
Thank you very much for your time and expertise.

[JackDo]