PTFE Rod: a Plug Sintered in Boiling Retene Vapour (Brubaker & Hanford 1946)

The first example of du Pont's way to shape PTFE: press a small rod of powder cold, then heat it above 327 °C out of the mould. Here the heat comes from the vapour of boiling retene, which boils at 394 °C, so the temperature holds steady by itself. The plug comes out sintered into one tough piece. Source: M. M. Brubaker and W. E. Hanford (du Pont), US 2,400,099 (1946), Example I. The pressure is the patent's usual range, as the example gives none. The mould, press and the vapour-bath set-up are ours. Picture drawn by Youblob.