Wetting agents in metallography

Wetting agents, also known as surfactants or surface-active agents, have been used by metallographers to modify etching speed or selectivity. Zephiran chloride, for example, is added to picral to increase etch speed and to etheral-picral solutions to aid in the detection of temper embrittlement. Other wetting agents, mainly sodium tridecylbenzene sulfonate, have been added to aqueous saturated picric acid to reveal prior-austenite grain boundaries. This short communication reviews studies of wetting agents for modifying etch behavior, describes the nature of wetting agents, and lists some manufacturing sources.