Aluminum foil is a traditional material for wrapping meat. Foil is easy to handle, and most people have it in their kitchen. Foil creates a tight seal that traps heat, speeds up cooking time, and does not allow further smoke to infuse the meat. The meat’s juices are reabsorbed when removed from the smoker, but this trapped moisture also creates a softer, less crunchy bark. The main thing for me if using foil is to ensure the bark has set so it doesn't wash off when you wrap the meat. That's usually around 180°F to 185°F (82°C to 85°C) internal temperature.