Picrate

[1][2] The picrate ion is intensely yellow, although many of its salts are brown or orange-red.

Picrates of some metals tend to be significantly more sensitive to impact, friction and shock than picric acid itself.

As a result, storage of picric acid (or mixtures containing it) in metal containers is strongly discouraged due to the high risk of accidental explosion.

Ferrous picrate is used in some applications as a diesel fuel additive to achieve better mileage.

[3] Sodium picrate is used as an etchant in metallography to differ preeutectoid ferrite in hypoeutectoid steel from preeutectoid cementite in hypereutectoid steel by etching cementite to a dark colour, whereas not attacking ferrite and thus it remains reflective.