Complex sentence: Rags used for Danish oil have some potential risk of spontaneous combustion and starting fires from exothermic oxidation, so it is best to dry rags flat before disposing of them, or else soak them in water.
Split into simpler sentences: Rags used for Danish oil have some potential risk of spontaneous combustion and starting fires, from exothermic oxidation. So it is best to dry rags flat before disposing of them, or else soak them in water.