Never mind - just cleaned the rack, it was definitely rust, not grapes, floating in the water. I'm usually pretty careful about leaving the rack in the water just til it's cool enough to pull out. But I left the canner on the stove (burner turned off) while we were gone last night, the water (and stove) were still warm when we got home so I pulled it off and let it sit overnight. Guess 18 hrs was too long to let that rack sit - cleaned it with steel wool, but it's all down hill from here.

I do wonder why I have more headspace after I take off the rings (not even totally cool/set yet). Do you think I'm getting boilover, or is it just the stuff I process (tomato sauce, salsa, jam, jelly) condenses as it cools, or cooks down in the canner (or both)? I hate to push it and risk boilover (though I have made some batches that I have carefully measured proper headspace with the bubble freer, and it still looks like I've got double that amount headspace after I pull it out, so maybe I'm not going to get boilover unless I fill it to the brim!).

Proper headspace is important. Not something to be guessed at or estimated.

So IF your headspace is right when the jar goes into the canner but is less when it comes out then there is a possible problem. The chart linked below discusses all the possible causes.

Starch foods will absorb some liquid but not things like tomato sauce, salsa, jam and jelly. With them, if you begin with the proper headspace, if you don't overpack the jars with solids (salsa), and if your bands are screwed on properly the headspace before and after should be the same.

Don't remove the bands until after the jars have completely cooled - 12-24 hours.

Dave

Here is a link that might be useful: Problems with Canned Foods - Loss of liquid

I've read that, Dave, that's why I tend to leave a little more headspace than recommended, if I don't measure it exactly every time. Err on the side of caution and all. But I have a pretty good eye for small measurements b/c of woodworking (I just can't estimate miles/acres!) As I said, I haven *noticed* any boilover. I free bubbles in jam and salsa, etc. but I leave jelly alone (fill all the jars, then go back and skim the bubbles off the tops of all with a spoon before putting lids and rings on. I make sure the rings are finger-tight, and I don't mess with them for at least 6 hrs (but usually have to move them before 12, definitely 24, I can't tie up the kitchen counter that long). I haven't had a jar unseal from removing rings before 24 hours.

So why does it seem that no matter how much headspace I leave, no matter what the product, I always have double the space after cooling? Oh, I take that back - the pickles I pasteurized seemed the same. Everything I *boil* in the BWB ends up double.

Am I maybe getting boilover without realizing it b/c pressure/temp on my glass-top stove isn't consistent? Has anybody else with glass top noticed this?

I haven't kept stuff long enough (just made my first batch of jam 4 months ago) to have anything mold or discolor due to too much headspace.

Oops, typo - should have been 3/16" in first post, not 3/18" - I'm not *that* good LOL!

What I meant to say was there was a typo, I meant 3/8" is what I tend to leave for jams and jellies (instead of 1/4"), but this jar of grape jelly was more like 3/16" b/c I *was* pushing it (had that stuck in my mind as I was typing the correction).

I still don't think I got boilover since the jar isn't sticky and I leave the jars in the canner for 5 minutes after turning off the heat and taking the lid off. But maybe I *am* getting boilover (though this time was definitely rust), and it's just washing away in the boiling water so i don't notice it with jelly (or pickles), though you'd think I'd notice little bits of stuff with salsa, jam, maybe pickling spices?

Well I assume you have read the NCHFP FAQs including the one on the importance of proper headspace, right? So I can only reiterate that it is important for safety.

As to boil over, depending on the food, it is quite easy to have boil over without getting sticky jars. It is the increased headspcae in the finished jar that is the clue to boilover happening, not the outside of the jar or whatever may be in the water. And as you saw on the "Problems" page I linked, there are several possible causes.

The recommended 1/4" for jams and jellies has always worked well for me. Some salsas are 1/2" and some are 1". It all depends on the amount of solids in the recipe. Tomato sauce is the standard 1/4". MOre than that results in a weaker vacuum.

Hope this helps.

Dave

I left about 1/2" (maybe slightly more, but not below the bottom thread) for Annie's Salsa, and I forget what Ellie Topp's Tomato Basil sauce was but I followed the recipe on that. It's just a shock to take rings off jelly jars or pickles and find the liquid just above the bottom lip, or even lower, just barely hidden by the ring, when I know I filled them to somewhere in between that and the top thread (1/4" plus or minus 1/8")!

Applesauce seems not to have increased (or that much) headspace, but the headspace isn't clear, you can see where it's boiled up. I'd have to really look at apple butter I have left - I don't remember off the top of my head how much headspace is left, but both apple products and tomato products boil up and leave residue in the headspace. Pickling spices get left up there too, and pickling liquid is reduced so headspace is almost doubled.

Since even the jars I have measured dead-on have increased headspace (not quite double, for example I leave 1/4" for jelly and then later it ends up just at the bottom thread which is almost 1/2") after processing, and I'm careful about the rings and such, the only thing I can think of is that the pressure/temperature is varying? Is this a problem with glass-top ranges? I've only had 1 jar (apple butter) come unsealed (within a week) so it seems vacuum is OK, but I don't really like having pickles sticking up above the brine, residue in the headspace area on apple & tomato products, and just lots of empty space at the tops of jelly jars.

Some glasstops are notorious for canning problems. It's not all brands but those that cycle on and off to maintain an "average" temperature are a real challenge for canners.

You might be better off with an old electric stove in the garage or basement or perhaps some sort of propane burner setup. (Obviously with the propane burner you have to take the appropriate safety precautions.)

Carol

our glass top cycles of and on ... had to get rid of two of the blue graniteware canners and use a stainless flat bottom stockpot ... with an aluminum core bottom. fortunately fits perfectly with about an inch overhang all around... heats relativelly quickly and holds the boil. Am still looking for a rack that fits AND supports jars properly. I have more trouble before jarring... have 6 quart triple core stockpot, but when it gets going, it's almost impossible to maintain a low heat, so things thicken too soon.

I have a 16-qt stockpot with triple ply bottom, so it holds heat (as I found when I left it on the burner the other night!), though it's slow to boil so I have to start it when I start the jam/jelly. If I leave it on High, it boils vigorously - too vigorously? - and water splashes out when I'm doing quarts. I can maintain the boil (unless I have a lot of jars, I found then that it will slow down/stop due to cooler food) if I turn it down to Medium, but I wondered if that could drop pressure. I've been experimenting, though, and it doesn't seem to make a difference. Since I only had this one half pint (and another empty that I left in there) the water wasn't too high (higher than I normally use for halfpints b/c I had just sterilized the quarts), so I just left it on High and it still looks like I might have had boilover of that one jar since the headspace is down to the bottom of the (continuous spiral) thread, not quite down to the "lip" that the ring rests on. But that may be b/c I overfilled this - left more like 3/16" instead of 1/4" since I didn't have enough for two halfpints.

Kay - do you have headspace problems? I know you don't do jellies, and you freeze pickles, but what about your chutnies (sp?)? I thought you ordered a rack? Are you still *looking*, or just waiting for delivery?

I ordered, but it hasn't come yet ... scheduled delivery Dec 1.

Don't have much of a problem with the chutneys... usually have one jar that comes up short, so it goes in the fridge (processed if it's close)

My relishes do seem to come out of the pot a bit short of the 1/2" mark ... but I think that is shrinkage since my relishes are a bit chunky. I also think if the boil is too rolling, jars occasionally vent a bit of the liquid along with the oxygen. Either that happens or I didn't wipe the outside of the jars as well as I thought I did 'cause the water is a bit discolored but not from the rack. I had a jar break in the pot one time and those jars had to be washed three times after cooling. It was a jar of green tomato relish and you know how we Southerners love our sweet relishes.

K