Etched brass plaques with black-filled text are made using a process called chemical etching. This process involves using a photo-resist material to transfer the design onto the brass surface, which is then etched away using a chemical solution.

Here are the steps involved in making an etched brass plaque with black-filled text:

1. Design creation: The first step is to create the design for the brass plaque using software such as Adobe Illustrator or CorelDRAW. The design should include all the text and graphics that will be etched onto the brass.
2. Transfer the design onto the brass: The design is then printed onto a transparent film, which is placed on top of the brass plate. The plate is then exposed to ultraviolet light, which causes the photo-resist material to harden where the light hits it. The unhardened photo-resist material is then washed away, leaving the design transferred onto the brass.
3. Etching: The brass plate is then submerged in a chemical solution that etches away the exposed areas of the brass plate. The depth of the etching can be controlled by adjusting the strength and duration of the chemical solution.
4. Filling the text: After etching, the plate is cleaned and any remaining photo-resist material is removed. The text is then filled with black ink or enamel paint. This makes the text stand out and provides contrast against the brass background.
5. Finishing: Finally, the brass plaque is polished to remove any imperfections and to give it a smooth and shiny surface.

Etched brass plaques with black-filled text are a popular choice for memorial plaques, nameplates, and other types of signage due to their durability and professional appearance.