Here's why:
* Brass is an alloy: Brass is typically made from copper and zinc, and variations in the proportions of these metals create different types of brass with specific properties. There's no established "Flemish" brass composition or standard.
* Flanders and Belgium: The term "Flemish" usually refers to the people or culture of Flanders, a region in Belgium. While Belgium has a strong history of metalworking, there's no specific brass tradition tied to the term "Flemish."
* Possible Misinterpretation: It's possible someone is referring to a specific brand or manufacturer of brass instruments in Flanders, or a particular style of brasswork.
If you have more context about where you encountered this term, it might be possible to clarify its meaning.