The main component is a tea-brown extremely stinky solution of dissolved iron in acetic acid (vinegar) that is called "Kanemizu" (Iron Paste Water), to this, the so-called fushiko or gallnut powder is added and mixed, then a hydrophobic solution is the result.
主成分は鉄漿水（かねみず）と呼ばれる酢酸に鉄を溶かした茶褐色・悪臭の溶液で、これに五倍子粉（ふしこ）と呼ばれる、タンニンを多く含む粉を混ぜて非水溶性にする。