are contemplated prosthetic grafts including air jet textured yarns are expected to possess an advantageous combination of strength permeability tissue ingrowth and ease of handling air jet texturing is a technique illustrated in fig3 for imparting bulk to a yarn by jetting a high pressure stream of air 14 against a sheath yarn 16 which loops and tangles the sheath yarn about an underlying core yarn the sheath and core yarns each of which may include one or more yarns are fed into a texturing chamber 18 at a faster speed than they are removed the rate of overfeed which may vary from 7 to 15 percent for the core yarn and from 10 to 30 percent for the sheath yarn provides a filament slack or excess in the texturing chamber which becomes tangled by the turbulent air flow adjusting the overfeed differential and the level of air pressure in the texturing chamber may vary the number and size of the loops the looping effect increases as the difference in the relative overfeed between the core and effect yarn increases an increase in air pressure also encourages looping of the filaments as well as compacting of the core yarn wetting the yarns in a water chamber 20 before entering the texturing chamber removes spinning finishes and reduces interfilament friction encouraging filament entanglement downstream of the texturing chamber.