A primer on Japanese steel
Originating
from the culture of sword making, forging metal in Japan is a fine art.
Trowels are produced from steel of various temperaments, ranging from
"soft" iron known as jigane to "hard" high carbon steel known as honyaki
(literally fully fired). Between these two extremes are a variety of
steels including hanyaki (literally half fired) and aburayaki (literally
fired with oil).Choosing the right steel for you depends on your purpose：
Jigane is unfired forged iron. Whereas a hard carbon steel tends to slide over a plaster, "soft" jigane iron will push and pull material, making it excellent at distributing plaster on wall. By "soft", we refer to the quality of the steel, not the flexibility of the trowel. Because Jigane is a soft steel, Jigane trowels tend to be thick, stiff and heavy. Jigane is suitable for scratch and brown coats of earthen or lime plaster.
Hanyaki is fired once after forging. Hanyaki is suitable for all coats, and can also be used for cement based plasters as well.
Abarayaki is steel that is forged, coated with oil, and then fired twice. It is harder than hanyaki and suitable for compressing plaster for a glossy finish.
Honyaki is made in a similar fashion to abarayaki, but is fired at a higher temperature. Being a very hard carbon steel, it is suitable for earthen or lime finish coats and cement based plasters.
Stainless steel is the hardest steel but can be produced so thin as to be flexible as well. It is used to apply thin coats and to smooth trowels marks.
Traditional steels will rust if not cared for properly. Trowels should be cleaned and dried immediately after each use. When storing trowels for an extended period of time, they should be oiled to prevent rusting. In order to prevent the remaining oil from discoloring subsequent plasters, remove oil with a rag before plastering.
