When cleaning fibers, always use a special optical cleaning fluid. It is however widespread, but forbidden, to clean fibers with alcohol. Too often fiberglass is cleaned with a rag and a bottle of alcohol. We are regularly confronted with this in our training courses. Alcohol is cheap and easily available. For years now, the IEC 61300-3-35 standard has prescribed that Isopropyl alcohol may not be used. The main reason: it attracts water, the glass becomes electrically statically charged.

Special non-flammable liquids that have been developed for this purpose give a better result.

With the naked eye you can see particles up to 50 microns (0.05 mm), but the core of a glass fiber is already 5 times smaller. Particles of 1 micron are already large enough to break the connection. Dust particles in the air are also often not visible.