Canning 101: What To Do About Spotty Or Filmy Jars

finished blueberry ginger jam

It’s been a long day of canning. You pull your last round of jars out of the canner and notice that they all have funky spots on them. There might even be a rough, funky film on the outside of the jars. You might be asking yourself if your jars are ruined.

Happily, the answer to that panicky question is no. Your jars simply have acquired some mineral deposits. This happens either when you’re canning in hard water or when your canning pot/rack is starting to break down.

The easiest way to avoid these spots and deposits on your jars is to add some white vinegar to your canning pot. I tend to use about a cup per canner load. It keeps the jars sparkling clean.

If you forget to add the vinegar, you can typically wash those spots and film off the jars once they cool. If it’s particularly strong film, you can fill your kitchen sink with warm water and a cup of vinegar and soak the jars for a few minutes. Give them a good rub with a rag or sponge and them let them dry. Should be good as new!

For more Canning 101 posts, click here to visit the archive.

 

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25 Responses to Canning 101: What To Do About Spotty Or Filmy Jars

  1. 1
    Ashley says:

    This definitely happened to me just the other day. I thought, how can my pantry be that dusty?! I think my canning pot is starting to break down, but it seems impossible to keep them from rusting- especially the rack.

  2. 2
    Angie says:

    My husband and I did our first jamming session a few weekends ago. I got those filmy spots of the lids and got the jars all sparkly again. But, I did notice that some of our lids have some rust spots right on the outer edge of the lid. I would like to know how to try and prevent this from happening. Could it be that the lids are the preparation bath too long? We removed the rings after the seal was made so no water was trapped between it and the ring.

    Last night I decided to use a little baking soda and a wet paper towel on the spots and it did help. So, I was wondering if you run into this problem and what could I do next time?

    I will be trying out some of your recipes in the near future and wanted to tell you that I am really glad I found your blog. It has been very helpful.

    • 2.1
      marisa says:

      Angie, I often experience that rusting, but I’ve not found a way to avoid it. Simmering the lids for just 10 minutes, as opposed to the entire preparation time does seem to help, but not always. I have found that it doesn’t do any damage to the finished product though, so I don’t worry about it too much.

  3. 3
    Karen604 says:

    I have been known to do a little touch up with Windex on the outside

  4. 4
    lynn says:

    I have noticed this is a problem with the newer, silver-colored lids. It was never an issue with the old gold ones. Bah!

  5. 5
    Katie says:

    Gah! I have such problems with our hard water that the lady at the store makes jokes about the amount of vinegar I buy. When I pull my jars out, the entire lid is coated with the dusty mineral salts (even with vinegar added), and I always have to wipe out my aluminum canner with vinegar to get rid of the film inside. At least it’s easier to clean than the shower…

  6. 6
    SherryGreens says:

    Mineral deposits here too, especially when we are up at the cabin using well water (very hard!). I will try some vinegar, good idea.

    I also just wanted to let you know that I have been so inspired by your blog, and this is my first time I have tried canning. I want to eat as much local food as I can, so canning is a big part of that. So far I have put up 130 jars, and counting! It is becoming ADDICTIVE.

  7. 7
    Joy says:

    Thanks for that great tip! I use vinegar and baking soda as a cleaner, but didn’t extrapolate the use of vinegar to something like this.

    Saw an earlier convo re canning vs freezing – where we live canning is THE way to go; we are subjected to regular and lengthy power-outages which are guaranteed to ruin the contents of the freezer!

  8. 8
    Rachel says:

    How timely! I was just noticing this week that my jar lids were getting spots and threw in some vinegar when I canned two nights ago – presto! No more spots! Can you do a post on the maintenance and care and life span of a canning kettle and canning jar racke, that is, when it has broken down enough that you shouldn’t use it anymore? I use a round cake pan cooling rack for my small batch setup and it looks filmy and discolored.

    • 8.1

      I would love a post like that as well! My first canning rack corroded after only one use and I’m noticing corrosion on my new rack as well. Apparently we have really hard water. I emailed Ball and they said it was okay to use, but it makes me nervous.

  9. 9
    wendy kreeger says:

    Marisa – I’ve been following your site for about a year and I’ve been truly inspired. However, I’ve been making jam for about 25 years, and I always used certo liquid pectin and generally followed their recipes, mostly with good results. But I’ve noticed most of your recipes have you cooking the jam with pectin for far longer than the pectin recipe’s 1 minute. Could you please comment on that?
    I did have more overcooked jam this past year when trying that method, probably my fault, waiting overly long for the sheeting action you discuss.
    Thanks
    Wendy
    Wendy

    • 9.1
      marisa says:

      Wendy, my recipes tend to be lower in sugar than those from Certo, so I’ve found that it is necessary to cook the jam for a few minutes longer in order to get a solid set.

  10. 10
    Marie says:

    Ahh, thanks! I knew the film was just from the hard water, but didn’t think there was anything to do but live with it….Will try the vinegar thing on the next batch!

  11. 11
    Alana says:

    I’m so used to the film on my jars- I’ve really stopped noticing it! I think it must be the old canning pot and the even older rack. But vinegar? This could revolutionize the whole thing! I could have sparkly jars after all?

  12. 12
    Sheryl says:

    Thanks so much for this post, I had this happen a few times this summer and it was irksome. Definitely going to try the vinegar next go around.

  13. 13
    Mama B says:

    Yeah, I think I need to buy a rack. Mine is permanently etched with mineral deposits (it belonged to my mother and isn’t exactly new). Thanks for the vinegar tip!

  14. 14
    Stephanie says:

    I actually use my homemade vinegar cleaning spray on my jars after they’re cooled if they have water spots, and then wipe it off with a cloth. That way I don’t have to use so much vinegar in the canner.

  15. 15
    Gretchen says:

    Thanks for the vinegar tip! I have been just wiping down the jars afterwards, but I’ll definitely try your suggestion. Thanks!

  16. 16

    I’ve never thought to add the vinegar to the water but always to a quick dip after the jars have cooled and set. A spray from the bottle of vinegar I keep for cleaning does a pretty good job, too.

  17. 17
    Heather says:

    Thanks for the vinegar suggestion! We have hard water, and I just figured the spots would always be unavoidable. Now I’ll have to try for sparkling jars next time I can something!

  18. 18
    Leone says:

    It is not a good idea to put the jars in warm water to clean them, I have had jars – unseal- in the warm water and then you have undone everything. Cool water and vinegar works well.

    Love your site. Love to can. Love to find new ideas. Thanks

  19. 19
    Illene says:

    I have been on your blog all afternoon. I just have to tell you how helpful you are! I just set a batch of chili apple jam this morning and when I took it out of the bath it had these spots on it and I did panic for a minute! White vinegar…great! I live in Florida and the water here is very hard. <3

  20. 20
    Terry Roy says:

    I am so glad I ran across this article. I don’t notice the film all the time; today I had it on the first batch of jars I processed but not on the second or third. It might have been because the quarts of crushed tomatoes were in the canner longer than the salsa and jam that followed.

    I’m glad to know this and love your blog and your book! I’m going to look for a new rack of stainless (like a cake cooling rack that you suggested, I believe) because the one I have is some kind of cheap dull metal anyway and made for a much narrower pot than the one I use.

  21. 21
    Jeannie says:

    I have been searching to find out what was on my jars, I canned salsa a few days ago, some of the lids have a…pale gold…color on the lids and bands. the salsa looks fine. My mom suggested the vinegar and the next/last batch was shiny silver. is the pale yellowish gold film on the lids and bands from water also? my Mom says yes but it scares me.

    • 21.1
      Marisa says:

      It’s a little bit of tomato juice that escaped from the jars and coated the jars. The vinegar in the pot the second time around helped keep any tomato residue from settling on the jars. It’s nothing to worry about.

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