Velhurs-Pearl, Pirt and Luedeking-Piret models during Tonon, R. Due to. D. V. . 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. 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. Influ- pharmaceutical, cosmetic and food industries. ; Hubinger, M. T. ; Brabet, C.