I have a question about head room in pressure canning.

[Emerald]

I was under the impression that while I can leave only about 1/2 to 3/4 of an inch of head room in water bath canning I should leave a good 1 inch head room (if not a tad bit more) when pressure canning. Some one told me that no, you don't need that much room.
I was told by my grandma that you need that one inch cuz pressure canning will bring the contents to a boil in the jar and if you don't leave enuf room it will boil out and possibly leave contents between the lid and the jar and ruin the seal..
Is that true and what have you all been taught?
Now I am on a quest!

 

[Farmfresh]

Head space depends much more on WHAT is in the jar being canned. Starchy foods like potatoes, lima beans, and corn that expand need more head space. Items like tomato sauce needs less and jams and jellies need the least.

It is important for the longevity of the product canned and the quality of the product that you always use the correct head space. Too little and BANG - too much and you end up with spoiled food after a while.

 

[Emerald]

Thanks! I was pretty sure that it was important to have the head room. Another poster who is learning to pressure can this week only left about 1/2 inch maybe less in her carrots that she canned and some one kinda poo-pooed be about the one inch head space being that important. Oh well. I just had to find out for myself what the deal should be. Thank you again!