Kilner jar

Kilner preserving jar The Kilner name goes back to a Yorkshire glassworks founded in 1842, and its first jar with a patented vacuum seal arrived in 1900. The vacuum seal is the whole design: heat drives the air out, and as the jar cools the lid is pulled down onto the glass by the vacuum inside rather than by the band alone. The jar pictured, from the 1920s, shows the glass lid and screw band. The original company went bankrupt in 1937; the Rayware Group bought the jar's patent, design and trademark in 2000 and still sells the range. Today's Kilner shelf runs well beyond preserving, from clip-top jars to drinks dispensers, so check that a jar is sold for home preserving before you trust it with jam.