What was found
AFTER TAKEOFF, A LAV SMOKE WARNING MESSAGE APPEARED ON EICAS. A SHORT TIME LATER A ODOR AND HAZE WERE NOTED IN THE COCKPIT. AFTER ACCOMP CABIN FIRE AND SMOKE PROCEDURES, EICAS MESSAGE WENT AWAY ALONG WITH THE ODOR AND HAZE. THE F/A CHECKED THE LAV AND BAG COMPT AND FOUND TO TRACE OF SMOKE OR FIRE. AN EMERG WAS DECLARED, THE PLANE RETURNED TO FIELD W/O INCIDENT. MX INSPECTED THE LAV FOR EVIDENCE OF SMOKE AND NONE WAS FOUND. SET UP THE A/C IN SAME CONFIGURATION AS IT WAS FOR TAKEOFF AND DID MAX POWER RUNS. THE A/C CHECKED OK NO ODORS NOTED. A TEST FLT WAS PERFORMED TO VERIFY NO FURTHER PROBLEMS. NO SMOKE OR ODOR WAS NOTED DURING THE TEST FLT AND THE A/C WAS RETURNED TO SERVICE.