Emp was placing door 5"" x 14"" (10lbs.) back into place at kiln riser duct 5th floor preheat tower. While tightening T-handle screw door slipped and started to drop employee caught door with Rt. hand on bottom of door which then caused the tip of his Rt. hand middle finger to strike edge of door below. X-Ray showed fracture to tip of finger. Emp was wearing heavy gloves