The two general types of strength-reducing defects most commonly found in lightguide fibers are those due to chemical interactions of refractory particles with the hot glass and those due to mechanical damage resulting from indentation or scratching. In this paper we review some work on the mechanical damage in silica lightguide fibers and some of the approaches which have been taken to simplify the study of such damage. We are reminded that the indentation and scratching behavior of silica glass is not simple and that in all probability there are a variety of different types of flaws which may have different fatigue and aging behavior, and therefore result in different lifetimes. It is therefore suggested that either the actual proof test level flaws, or at least a wide variety of synthetic flaws, must be studied in order to develop sufficient background and experience to confidently predict fiber lifetimes.
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