Sodium hydroxide

Sodium hydroxide:
10% sodium hydroxide is used rather then phenol.
NaOH is applied until area blanches (appear an ashen gray/brown colour – takes about 20-30 seconds), then dry, then neutralise with 5% acetic acid
Advantage of NaOH over phenol is reported as being more predictable, higher success rate, less drainage, faster healing times and lower recurrence rates