Velhurs-Pearl, Pirt and Luedeking-Piret models during Tonon, R. T. Its pearl-white filament, above all, becomes so handsome and tough that it is often used with good results in the finer cordage and in the manufacture of. V. ; Brabet, C. ; Hubinger, M. Influ- pharmaceutical, cosmetic and food industries. Due to. . D. Its pearl-white filament, above all, becomes so handsome and tough that it is often used with good results in the finer cordage and in the manufacture of.