How do you get a dark background and light raised areas on a relief carving?

Stain can creep along the grain, so I’d avoid brushing it straight onto the finished background unless you’re comfortable with some uneven edges. One option is to seal the carving first, then use a thin tinted coating in the recesses with a small brush. Try it on a scrap from the same wood, since the sealer and color can change the look and how well they adhere.

For a more natural look, you could darken the background first, then carefully sand the raised surfaces back. That works best if the surface is already smooth, and you’ll want to go slowly so you don’t round over the carving. Test the stain and sanding sequence on a matching offcut before committing to the piece.

If you want a crisp boundary, make a shallow cut around the raised shape before applying color. It can help keep a brushed-on dark color from wandering, though it won’t prevent every mistake. Another route is shading the recesses with a pyrography tool, but that’s permanent, so practice on scrap and build the darkness gradually.