Head space in Weck jars
I splurged and bought some Weck jars for canning. I purchased the .5 liter tulip jars. I notice that they have a substantially larger mouth than Ball/Kerr jars. They also appear to be both fatter & shorter. I tested with my canner, and can get only 5 jars per level instead of 6 jars with the Ball pint jars.
Does the difference in shape mean any changes I should adjust any recipes from the Ball Canning book? I am particularly wondering if the head space should remain the same.
Best Answer
I just checked the Weck (the manufacturer) website (German, sorry) and the recommended head space is
- Full if you are processing fruits or vegetables that get topped up with a liquid like water or thin sugar syrup.
- At least 1 cm headspace for mushy goods like apple sauce.
- At least 4 cm headspace for anything that swells up (sausage meat).
- Only half full for cakes etc. that get baked in the jars and then sealed.
The explanation by Weck for 1. is that all excess will just be pushed out during processing and that it won’t compromise the seal, anything with “particles” on the other hand could. Personally I always leave enough to be reasonably sure that nothing can get between the glass and the gasket, even for liquids - usually a generous half an inch or so for the use cases that fall under 1.
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How much is headspace in Weck jars?
The shape of the lid means it comes down about \xbc inch into the jar. For this reason, you never want your headspace to be less than \xbd inch. As a rule of thumb, you should add \xbc inch to the headspace your canning recipe calls for.How much headroom do I need for canning?
General canning headspace recommendations from the United States Department of Agriculture are as follows: Leave \xbc inch headspace for jams and jellies; leave \xbd inch for tomatoes, fruits and pickles that will receive a boiling water bath process; leave 1 inch headspace for most low acid foods that will be pressure ...Can you leave too much headspace when canning?
If too much headspace is allowed, the food at the top is likely to discolor. Also, the jar may not seal properly because there will not be enough processing time to drive all the air out of the jar.Why is headspace left in canning?
Answer. Headspace is the distance between the surface of food and the underside of the lid. Leaving the specified amount of headspace in a jar is important to assure a vacuum seal. If too little headspace is allowed the food may expand and bubble out when air is being forced out from under the lid during processing.How to determine HEADSPACE when CANNING
More answers regarding head space in Weck jars
Answer 2
I use the cylindrical jars from Weck and would say that the headroom can be kept the same in general. At the end of the day you just don't want any stuff to swell over and not have too little in there so it spoils. In my experience keeping about a fingers worth of space to the rim will not cause you any major issues.
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