Nital

Nital is a solution of nitric acid and alcohol commonly used for etching of metals. It is especially suitable for revealing the microstructure of carbon steels. The alcohol can be methanol, ethanol or methylated spirits.

SEM micrograph of lamellar pearlite in a eutectoid (0.8% carbon) steel after annealing. Nital etch.

Mixtures of ethanol and nitric acid are potentially explosive. This commonly occurs by gas evolution, although ethyl nitrate can also be formed. Methanol is not liable to explosion but it is toxic.

A solution of ethanol and nitric acid will become explosive if the concentration of nitric acid reaches over 10% (by weight). Solutions above 5% should not be stored in closed containers. Nitric acid will continue to act as an oxidant in dilute and cold conditions. [1]

References
  1. "An Explosive Nitric Acid-Ethanol Mixture". web.archive.org. 2016-03-05. Retrieved 2020-04-05.
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