Limestone Water – Nahm Bpoon Daeng
by Kasma Loha-unchit
See Also: Grilled Coconut Cakes (Kanom Paeng Jee), which uses limestone water.
Limestone Water (nahm bpoon daeng): A natural mineral water made with pink limestone is widely used in batters for fried foods and pastries as a key ingredient that promotes crispiness. It is also used to crisp up cucumbers for pickling and vegetables for salads.
To make limestone water, empty the contents of a small container of pink limestone, available from Thai and Southeast Asian markets, into a two-quart jar and fill with water. Cover jar tightly with a lid and shake to dissolve the limestone. Let stand 1 to 1 1/2 hours, or until the water has almost cleared. Use the very faintly pink water with fine particles of suspended limestone dust in the recipes that require this crisping agent.
Store the limestone and water remaining in the jar unrefrigerated in the pantry, adding more water and shaking the jar about an hour or so before it is needed again. One package of pink limestone will last you a very long time and keeps indefinitely. Discard when the solids settle in half an hour or less, indicating that the remaining particles are too coarse.
Pink limestone is also a main ingredient used in betal-nut chewing among traditional Southeast Asians unwilling to give up the practice of this once very popular pastime throughout China and Asia. Betal-nut chewing used to be a social activity and daily ritual engaged by people of all classes of society and was equivalent to tea time in England.
Our Ingredients Index contains links to many more Thai ingredients.
There's more information on Limestone at the She Simmers blog: The Use of Limestone Solution in Thai Cooking.