pct us07 79249 and pct us08 86460 or my prior u s pat nos 7 480 978 and 7 146 709 in one example the extruded and drawn filaments are cut or chopped into short segments typically 0 15875 to 0 63500 cm long at a chopping station 16 preferably the cut filaments all have approximately the same length actually the more uniform the filaments in size the better the chopped filaments are then passed to an etching station 18 where the ductile metal is leached away using a suitable acid for example where copper is the ductile metal the etchant may comprise nitric acid etching in acid removes the copper from between the tantalum filaments after etching one is left with a plurality of short filaments of tantalum 15 as shown in fig4 the tantalum filaments are then washed in water and the wash water is partially decanted to leave a slurry of tantalum filaments in water the slurry of tantalum filaments in water is uniformly mixed and is then cast as a thin sheet using for example in fig5 u201c doctor blade u201d casting station 22 excess water is removed for example by rolling at a rolling station 24 the resulting mat is then further compressed and dried at a drying station 26 it was found that an aqueous slurry of chopped.