Abstract:
The invention relates to a melt composition for the production of man-made vitreous fibers and man-made vitreous fibers comprising the following oxides, by weight of composition: SiO239-43 weight % Al2O320-23 weight % TiO2up to 1.5 weight % Fe2O35-9 weight %, preferably 5-8 weight % CaO8-18 weight % MgO5-7 weight % Na2Oup to 10 weight %, preferably 2-7 weight % K2Oup to 10 weight %, preferably 3-7 weight % P2O5up to 2% MnOup to 2% R2Oup to 10 weight % wherein the proportion of Fe(2+) is greater than 80% based on total Fe and is preferably at least 90%, more preferably at least 95% and most preferably at least 97% based on total Fe.