If they are actually canning jars then no problem. But I never saw irridescent pint and 1/2 jars - ever. So they may be one of the many crafting jars made to use for candles and such and not for canning.

On the other hand there are old blue Mason jars that may be used for canning though many don't given their age.

Dave

They're all the 24 oz wide mouth Ball jars, this one just has blotches of iridescent color when I held it up to the light after taking out of the DW, to check that there was no stuck-on residue (they were pretty dusty when I bought them - spiders too).

The pint and 1/2 jars - the standard name for them - are considered a real find. Ideal for canning many things, especially asparagus, and were sadly missed by many. So much so that Ball just recently started making them again after a recent online survey - they are discussed in several long threads here.

Don't know the source of any iridescence - perhaps something that was once stored in it in which case it should scrape off or boil off in vinegar. Otherwise they should be fine for canning. They are processed using the quart times.

Dave

Yes, thanks, I know they are real finds (I have 10 or 12 now), and was one of the petitioners to bring them back. I'm going to try some pickled okra this year (though probably don't need such a tall jar since I want thumb-sized pods). What I find that size perfect for is spaghetti sauce - Ellie Topp's recipe with red wine - for our family of 4. Means I can get rid of the Classico jars I've been using (of course using quart time)!

I know they just brought them back for $12 for 9 jars, glad I found them for the price I did.

Nothing to scrape - but I will try boiling jars before using. Only noticeable in the sunlight (when clean), was just wondering if it was a chemical change in the glass and could mean it was weakened.

Glass can change color in natural ways. Exposure to sunlight can change the color of glass as will exposure to soil. Jars buried in the soil can become iridescent.

These are all natural chemical reactions and vary depending upon external conditions and the minerals in the glass. An example would be a kerosene lamp which turns purple as it ages due to a chemical reaction between sunlight and the manganese in the glass.

I don't know how it's currently made, but I know Ball used to use a certain % of cullet in its glass jars and the chemical composition would vary depending upon the source of the purchase.

Cullet is broken old glass (like windows or soda bottles, etc.) which is mixed with the fresh ingredients to make "new glass." The cullet is required to assure an even melt in the furnaces.

So all canning jars have some slight variation in the chemical composition depending upon the composition of the broken glass being used and that influences the response of the glass to sunlight, minerals (like that in dishwasher detergent or water) or soil.

It's not harmful and there's no reason not to use the jar but my inclination would be to use it in boiling water bath rather than pressure canner in case the iridescence is due to excessive heat, which might have weakened the glass.

Carol

Thanks Carol. I don't think these were buried in soil (they weren't THAT dirty LOL!) but since these are older maybe they had been exposed to a lot of sunlight, don't know why only 1 seems affected but I will keep an eye on all of them. We'll see if I make dill spears from some bigger cukes this year, I might use them for that.

I would love to get a new PC and start canning soups and such, but will be careful to use new jars (probably would need quarts - my family eats lots of soup!) for that.

I think the key might be the dishwasher. Glasses often get a deposit on them when they've been through the dishwasher (which you say yours did). Was the rinse aid and salt topped up? Did you use the correct programme? We wash all our drinking glasses by hand now because of problems with discoloration. But I believe it is only superficial, not a change in the glass itself.

If you soak the glass in vinegar does the clouding go? If not the glass has been etched permanently.

The jars are the same design but not necessarily the same batch or run so that single jar may have a slightly different composition than the others you obtained.

Carol

When you go to use them for the first time I would use only one or two. Go from there on your results.

cancel my previous thought. If only one, try canning water in it the first time.

It's not etching (not cloudy), and it's only the 1 jar so I think Carol has figured it out.