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nigrescence n.變黑;(顏色;皮膚;眼睛等的)發黑。

nigrescent

Reshi chemicals is a specialist in manufacturing and distributing metal surface treatment reagent : phosphorus treatment reagent , water treatment reagents , electro - plating additive reagents , normal temperature nigrescence reagent , pre - treatment reagents , etc 是一家專業從事金屬表面處理藥劑:磷化處理藥劑、水處理劑、電鍍添加劑、鋼鐵常溫發黑劑以及前處理產品的生產商和代理商。

Carbon channel is usually finished with electro - galvanization . hot dipped galvanzined finish or epoxy coating or nigrescence is also available on special order 碳鋼型鋼的表面處理普通為電鍍,如需熱浸鍍鋅、噴塑、發黑等要在訂貨時說明。