Sputum Type Appearance Cause Serous Clear, watery, frot Acute pulmonary hy, may be pink oedema Mucoid Clear, grey, white, Chronic bronchitis Asthma Purulent Yellow, green All types of brown bacterial infection Rusty Rusty, golden Pneumococcal yellow pneumoniaType Appearance Cause Serous Clear,watery,frot hy, may be pink Acute pulmonary oedema Mucoid Clear,grey,white, Chronic bronchitis, Asthma Purulent Yellow, green, brown All types of bacterial infection Sputum Rusty Rusty,golden yellow Pneumococcal pneumonia