coating of the present invention comprises 85 to 95 hydroxypropyl methylcellulose and 5 to 15 polyethylene glycol the most preferable combination is about 90 hydroxypropyl methylcellulose and about 10 polyethylene glycol these percentages and all of the percentages set forth herein are by weight unless otherwise specifically stated the coating is applied to the fibrous vegetable material as about a 5 solution in alcohol with a minor amount of water the most preferable fibrous vegetable material comprises psyllium powder psyllium powder comprises the ground husks of the seed of the plantago ovata plant species the husks consist principally of the colorless epidermis of mucilage containing cells any similarly powdered fibrous vegetable material which serves as a bulking agent and for which dispersion in water does not readily occur naturally could also be used in the present invention preferably the psyllium powder is of a 20 to 200 mesh u s series sieve particle size the precise particle size distribution for a preferred psyllium useful in the present invention is set forth in table i below ______________________________________ percent by weight of powdered psylliumu s series seive mesh no remaining on screen______________________________________20 030 10 340 23 960 47 280 12 8100 2 9200 2 7pan 2______________________________________ as can be seen by reference to table i it can be said that the psyllium most preferably comprises from about 20 to about 80 mesh particle distribution since the bulk of the material falls within that screen range the density of a suitable psyllium powder loose is approximately 0 44 grams per cubic centimeter tapped the same material has a density of 0 50 grams per cubic centimeter to coat.