High pressure injection syringe

A method comprising the acts of:

• advancing a plunger against air in a syringe chamber, wherein the plunger has a seal seat having a bottom surface, a collar adjacent to the seal seat, and a seal member disposed on the seal seat and sealingly engaging an inside surface of the syringe chamber, wherein the seal seat is a circumferential groove and wherein during the advancing, air is aspirated out of the syringe chamber across the bottom surface between the seal member and the bottom surface;
• and
• subsequent to the advancing, continuing to advance the plunger in the syringe chamber to engage a viscous material in the syringe chamber, whereupon the viscous material presses the seal member against the collar forming a seal against escape of the viscous material past the seal member.

An apparatus comprising:

• a syringe chamber comprising an inside surface;
• and
• a plunger comprising a collar, a seal seat having a bottom surface extending transverse to the collar, a groove extending across the bottom surface, and an O-ring having an inner surface disposed on the bottom surface and an outer surface sealingly engaging the inside surface of the syringe chamber, wherein the bottom surface, the groove and the O-ring are cooperable to vent air from the syringe chamber through the groove past the inner surface of the O-ring during advancement of the plunger into the syringe chamber against air, and wherein the O-ring is responsive to seal against the collar during advancement of the plunger against a viscous material in the syringe chamber sealing against escape of the viscous material past the O-ring.