The benefits of using sharp knives and lawn mower blades may seem to be obvious. Of course, sharper blades will cut better, but there are also other benefits.
Dull knives are one of the most common causes of stress injuries to the wrist, hands and arms. These injuries are caused by putting undue pressure on these parts of the body as additional effort is needed to cut with a dull knife. A sharp knife reduces this stress and will prevent these types of injuries.
Dull mower blades rip and pull grass instead of cutting it cleanly. This damages the grass which can cause it to turn brown. A dull blade also gives your lawn an uneven cut.