Braided flax fiber impregnated with wax has been packing stuffing boxes for a century and is still used today. “That wax starts to break down around 120 degrees,” says Jack Laurain, owner of Western Pacific Trading (www.wptinc.net). His company produces much of the packing sold worldwide. “The flax gets rigid and won’t seal.”
In the 1960s Teflon replaced wax in flax packing. “PTFE (the generic name for Teflon) has lower surface friction and high heat tolerance. It can withstand temperatures beyond 200 degrees,” Laurain says.
In the ’80s graphite-lubricated Gore fibers gained popularity. “Graphite is a very good lubricant, and the fibers are much stronger than flax,” Laurain says. “The Gore fibers also conduct heat, dissipating it through the stuffing box.”