What's the plural form of surmoulage? Here's the word you're looking for.
Answer
The noun surmoulage can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be surmoulage.
However, in more specific contexts, the plural form can also be surmoulages e.g. in reference to various types of surmoulages
or a collection of surmoulages.