How can I avoid lid buckling or dimpling when I water bath?
This is a sign that pressure has built up inside your jar during the water bath. It is VERY important that the steam is allowed to vent properly during water bath. Whether you are using 2-piece lids or 1-piece lids, the same principles apply.
There are 2 main causes, both of which can result in a compromised seal and/or a lesser vacuum than expected.
Why is Venting Important?
During the water bath, the venting drives out the steam from the headspace. This accomplishes 2 vital tasks.
Following the proper headspace guideline for each product is also important and can influence proper venting & sealing.
In the picture above the preservers are using 3 nifty tools; Magnetic Lid Wand (to retrieve canning lids from the hot water); Canning Funnel (with wide mouth to help avoid spills and dripping; And a Bubble Popper/Head Space Measurer. These tools are part of the 6 Piece Canning Set.
Too little headspace: Food particles or juices may be forced out of the jar. As this happens, you not only end up with a mess, but you will likely get spoilage and/or a compromised seal. Any particle caught in between the liner & the jar can act as a conduit of air & contaminates into your jar.
Too much headspace: Too much oxygen will remain in the jar = more oxidation of your product = darkening or browning in the top layer of your product. This practice also is likely to decrease the potential vacuum of the finished product.