Just curious if you have experience with pouring boiling water into glass jars?

Dunno in general, but with canning jars (i.e., Kerr) that's how you sterilize them.

Glass jars can easily take the 200 or so degrees of hot water. What will do them in is thermal shock where it is heated too quickly in one spot compared to other spots. As in a flame, for instance. or freezer to oven or reverse.

Glass jars are heated fairly high when filled with the contents and sealed. Heat killing bacteria is what allows it to keep product safe.

Review: Over 150 incidents of glass 'bakeware' shattered (some with serious injuries).

Borosilicon (often made in Europe) versus soda lime (which is more shatter resistant).

They filled bakeware with dry sand, baked at 450 degrees F for 80 minutes, and then put it on wet graniteand.

The result was that 10/10 times the American-made soda lime bakeware broke while the European Borosilicon didn't break (but most did at 500 degrees).

Revealingly, the ancient American Borosilicon did last at 500 degrees.

An unexpected bonus was the fact that the glue under the wrap-around label heated up enough to be easily balled off with a kitchen utensil.

Maybe we accidentally found a way to remove the under-label glue without solvents!

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I agree. I've poured boiling water into glass containers over the years and never saw one shatter either. I still do it carfully though. I think the reverse is worse, ie quickly quenching a hot glass.

Like most materials, glass expands when heated. Heat breaks glass vessels when the glass is nonuniform, i.e. has varying densities at various places. If some parts expand faster than others, this introduces stresses that may break the vessel. It is generally supposed that older glass vessels are more uniform than modern ones, thus can accept more heat without breaking.

As others point out, it is the thermal stress that breaks the glass. Pyrex type glass expands less and will take more stress but is too expensive to use for throwaway jars. The cheap jars if heated slowly and uniformly to minimize stress will take hot filling. In your case, adding the hot water slowly with swirling would probably be OK.

Also not a good idea to microwave items in this type glass.

Take that jar out of the freezed and splash some boiling water into it, and it will react totally differently!!

Owens-Corning sold the Pyrex brand name to a company that's now using it for soda-lime glass (not heat-resistant).

I once canned some peaches and didn't get the air bubbles out of the jars before putting them in the canner. The bottoms of the canning jars popped off very neatly, as though they'd been cut with a glass cutter.

You probably had the lids too tight to begin with...air is supposed to escape during the canning bath and then the lids seal as the jars cool. Should tighten before boiling so that the rubber seal barely touches, not tight. The rings, if separate, are then tightened after cooling. Test lid with a tap ..

The major issue with any kind of glass is even heating and cooling. One t'giving, getting the turkey ready, I moved an empty Pyrex pie plate onto a burner on our glass cook top. Sat down to dinner in the dining room and a couple of minutes later there was an explosion in the kitchen. The burner had been left on, and there were long shards of glass all over the kitchen. Don't want to know what it would have been like if one of us had still been in the kitchen.

Learned from glass crafting that various glasses have differing COE (coefficient of expansion, I think)...can put glass in a kiln to melt or fuse it, but two different glasses to be fused should have same COE or they cool at different rates and then crack. Took grandson to a glassblowing class...way cool. He had thought about being a glassblower but decided to make it just a hobby :o)

Didnt know there was soda glass bakeware made in USA. Pyrex isthe only glass bakeware I know of.

Jimmie

Well, not all "glass" is the same.

Pure quartz glass has a very low thermal coefficient of expansion. Standard "Soda-Lime" glass has a relatively high thermal coefficient of expansion.

The "Boru-silicate" glass features a thermal coefficient of expansion close to pure quartz. It's advantage over quartz is a MUCH lower melting point.

The original American Pyrex (r) was a Boru-silicate glass. Apparently, the owners of the trademark decided that in the US market they would use "tempered" soda-lime glass in place of the Boru-silicate glass.

The Tempered glass is good stuff. It's very, very break resistant and is moderately resistant to thermal shock. (It's actually created via a "thermal shock" process whereby the hot glass surface is suddenly cooled; another process uses a "case hardening" process when Potassium (K) replaces Sodium (Na). The potassium atom is a bit larger ad that places the surface under stress which has the same effect as quickly "tempering" the glass.

The neat thing about tempered glass is that when it does break it breaks into small pieces which are unlikely to cause a fatal injury. OTOH, true Pyrex (r) will, when broken, generate good sized slithers.

The types of lawsuits generated by broken tempered glass are as in the noise as compared to that generated by broken soda-lime glass.

Watch out for broken tempered glass! While external to the vehicle, I had a front windshield shatter, in moving about the vehicle to retrieve items on the front seat, I gently brushed my back against the shattered widnshield. I did NOT even feel the small shards cut through my shirt and down into flesh until someone pointed out the blood running down my back. So yes, not fatal, but still as sharp as a scalpel.

I've had that happen to me with glass drink bottles - probably bottled iced tea as you'd buy at a gas station on a road trip or something. You know how you get that cool "smack" sound when you hit the lid with the flat of your hand? I just picked up a bottle out of the cooler, idly smacked it for no real reason, and the bottom of the bottle popped off and landed on the ground. Fortunately I was not in a car but standing in a parking lot when that happened. I haven't done that since :)

nate

The Consumer Reports article implied there is Anchor Hockings and Pyrex and that Pyrex is no longer made by Corning (if I remember correctly).

Is the windshield tempered?

I know the sides are (and they do break into little pieces - ask me how I know).

But the windshield is laminated I thought. Not tempered.

My HS physics teacher used to do that as a demo. Think its also on Utube.

Jimmie

windshields aren't tempered.

i have buckets of chunks of tempered glass. i can run my hands through them without any cuts.