.........because you apply it after cutting the lenses.
For the price of a few cents per lens you can treat an easy 200 pairs with a one liter bottle (during its shelf life) and it provides also anti stat and anti fog properties, which none of the others do.
material description: http://www.eng.buffalo.edu/Courses/ce435/Polysiloxanes/
products description: http://www.optochemicals.com/product...ydrophobic.htm
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