Mechanical action and abrasion

In detail

Chemistry gets the attention, but a great deal of cleaning is mechanical: agitation in a washing machine, the wiping of a cloth, the scrubbing of a brush. Mechanical action breaks soil away from a surface, moves fresh cleaning solution into contact with it, and carries loosened material away. It also substitutes for other variables — more agitation can compensate for lower temperature or milder chemistry, which is the principle behind cool-water laundry cycles running longer. Abrasion is mechanical action taken further, using particles hard enough to cut into a deposit. The governing question is always relative hardness. An abrasive softer than the surface removes the deposit and leaves the surface intact; an abrasive harder than the surface removes the deposit and scratches whatever is underneath. This is why a fine, soft abrasive is safe on glass while a scouring pad is not, and why the same product can be right on one part of an appliance and wrong on another. Directional finishes add a second consideration: on brushed metal, working across the grain leaves marks that working along it does not.

Why

• Wood ash is explained by Mechanical action and abrasion
• Mild abrasion is explained by Mechanical action and abrasion
• Cleaning along the grain is explained by Mechanical action and abrasion
• Mild cream cleanser is explained by Mechanical action and abrasion
• Soot is explained by Mechanical action and abrasion
• Blotting is explained by Mechanical action and abrasion

  Explained by the absence of lateral force: rubbing drives the spill deeper, spreads it outwards, and abrades the surface itself.

• Coated spectacle lens is explained by Mechanical action and abrasion