Currently I am using a 3 wt% concentration of nital to etch quenched 1050 steel. The martensite grains become visible but difficult to see for grain counting. I do not want to use picral due to its safety hazards. Based on the research I've conducted thus far, sodium metabisulfite (SMB) is a better etchant than picral for revealing martensite grains if viewed using partially crossed polarizing filters with a sensitive tint plate. Does anyone have other suggestions for etchants and imaging modes to view martensite?

Thank you all very much for the input.