silicon paper like product may be formed into any of various geometrical shapes including pleating and incorporation into a regeneratable filter for carbonaceous products contained in a gas stream carbonized cotton fibers as opposed to carbonized pan fibers or other organic carbonized fibers is an important aspect of the present invention for reasons not known with certainty all non cotton carbonized fibers known and available to the present inventor fail to yield the desired silicon carbide fibers as opposed to whiskers as noted the useful cotton fibers should be cleaned and bleached cotton fibers which have been carbonized examples of suitable carbonized cotton fibers are those available from e amp l enterprises inc of oakdale tenn or aerospace enterprise inc of gardner me and identified as aei 1000 degree c carbonized cotton fibers raw non carbonized cotton fibers have been found to exhibit unacceptable mixing characteristics in the present invention even when added to the mix in relatively smaller proportions of a mixture of carbonized and raw cotton fibers for use in the present invention the cotton fibers are chopped following their carbonization to individual fiber lengths of between about one eighth to about one half inch the silicon carbide fibers.