The brush knots are knotted to 75% of the length. The brush is designed for brushing large areas and for heavy-duty brushwork, such as deburring, cleaning, derusting and descaling, as well as removing spatter. Steel wire is the most common filament material. Brushes with steel wire as the filament material are ideal for work on surfaces and deburring. PFERD special wire has high tensile strength and bending fatigue strength. This ensures that the wire wears down in the optimal way, as well as a long tool life, even in extreme brushing applications. Steel wire is temperature-resistant up to 600°F.