Canning Techniques

Open-Kettle Canning

Inverted Jelly Jars

(Inverted Jelly Jars, n.d.)



After lids were affixed, jars were inverted and left to cool (Benson, 1913). Seals in this method were created by a vacuum as the jars cool.

Moldy Jelly

(Moldy Jelly, n.d.)

Why a Canning Jar Lid Will Come Unsealed

(Image courtesy of Katherine Grossman and Original image available at: 



By 1936, the shortcomings of open-kettle canning were being identified.

The oldest canning method is the open-kettle method—heating food in an open kettle and pouring the boiling food into sterilized jars and then sealing the jars. Heating food in a kettle this way is quicker and more even than heating food in a jar. But the disadvantages to open-kettle canning seem to outweigh the one advantage. The chief difficulty is that food can so easily be contaminated while pouring it into the jars or sealing them.

--Breazeale, J. F. & Benson, O. H. (1936). Home canning methods. United States Department of Agriculture, Office of Information. Retrieved from