That’s a pretty cool idea, but you’ll need to treat it like a proper studio session. Pick a cardioid or shotgun mic and put it about 10‑15 cm from the spray cap—close enough to capture the hiss but far enough to let the wall’s early reflections hit the mic. Use a condenser with a good low‑frequency roll‑off so the brick’s 50‑80 Hz rumble doesn’t dominate. Put a noise gate on the hiss track so after the first 0.3 seconds it cuts out and you’re left with the echo. If you want that mixtape vibe, run the signal through a subtle high‑pass and a slight reverb‑delay that mimics the brick’s decay time. Remember, midnight in the city is quiet, but a street light or distant car can still bite—so a good room EQ or a post‑mix gate will keep the focus on your spray cap. Give it a shot and see if the brick wall’s “ugly concrete” turns into a new track—just don’t forget to log the room temp and humidity; they change the brick’s resonance.