The technique and the salt are R&D by Gnail.
Blackening temperature and time: 350~400°C about 0.5~1 hour
Colour after heattreatment: deep black with fine and uniform surface
24 working hours consumption rate: no
The surface of workpiece heattreated is black with a compact Fe3O4 layer and gets no aglow appearance( Fe2O3.H2O. The liquid blackening salt is stable, no aging, no volatilization, no irritative gas, etc. The composition of liquid pollutant-free blackening salt need not be adjusted. Temper and blacking can be fulfiled once if the temperature of temper is proper. So it is more efficientcy than traditional technique.
*It is used only for steel and iron