Apparatus and method for gel casting

A method for casting a polyacrylamide gel in a vertical gel enclosure having a bottom opening, said method comprising:

• (a) saturating a piece of smooth paper having a water absorbency of about 1 to about 6 grams per 100 square centimeters and a wet strength of at least about 25 psi, sized to cover said bottom opening, with a first aqueous solution of acrylamide monomer and a polymerization catalyst;
• (b) holding said saturated porous paper against said bottom opening until sufficient acrylamide monomer in said first solution polymerizes to form a watertight seal across said bottom opening;
• (c) filling said gel enclosure with a second aqueous solution of said acrylamide monomer and said polymerization catalyst;
• (d) polymerizing sufficient acrylamide monomer in said second solution to form a gel;
• and
• (e) removing said saturated porous paper from said bottom opening;
• the concentration of said polymerization catalyst in said first aqueous solution being from about two times to about eight times the concentration of said polymerization catalyst in said second solution.