Occasional fibres in my cultures - (Jan/29/2014 )

I sometimes get these things in my cell cultures that look like some sort of hair or other fibre. Am I introducing these myself or could they be a manufacturing anomaly introduced by something else?

plastic fiber from filter tips?

Possibly. I guess you mean from the filter rather than the tip? I'm not sure what the filter is made from in filter tips although it doesn't look like something that would shed fibres. On the other hand, the filters in the 5, 10 and 25 ml pipettes does look like cotton wool. Since these large pipettes are used in some of the stages of preparing/plating cells, perhaps they are introduced at that point.