Some Questions About Pyrex

[thock]

Actually, it can lose its temper, as in become untempered, if it's tempered glass. The newer Pyrex is now made out of tempered glass, not borosilicate glass, at least in the USA. In Europe, you can still get borosilicate Pyrex.

Tracy

[baroness]

From the pyrexware.com website: "PYREX® glass products are made using a tempered soda lime glass composite, as is the vast majority of consumer glass bakeware in the North American marketplace. The Cookware Manufacturers Association considers soda lime an appropriate material for glass bakeware."

Soda-Lime glass, whether 'tempered' or not, has no place in MY kitchen. It is heavier, weaker, and far more temperature sensitive than borosilicate. I'm grateful that I don't need any new pyrex-type items!

[Wholemeal Crank]

This is all so interesting to know!

I will continue to treasure my older pyrex, and be glad that I got a lot of my casseroles through thrift shops rather than new.

[MSRadell]

From the pyrexware.com website: "PYREX® glass products are made using a tempered soda lime glass composite, as is the vast majority of consumer glass bakeware in the North American marketplace. The Cookware Manufacturers Association considers soda lime an appropriate material for glass bakeware."

Imagine that, the Manufacturers Association says that a process can be used to make a consumer product! I wonder what the consumer product safety commission or some of the other consumer organizations think about this? It is certainly not as good as the original product, only cheaper.

[andiesenji]

I too have many pieces of Pyrex, FireKing, Glasbake and other glass baking dishes as well as some stovetop glass pieces that have survived since the 1930s without breaking.

I never subject them to abrupt temperature changes because I know that is specifically forbidden.

The instructions that came with the original glass cooking vessels specified placing the hot dishes on a folded DRY towel. Good advice today.

If the casserole was removed from a hot oven and placed on the stovetop, I assume it was placed on the burner grid. That metal works as a heat sink (unless it has been pre-heated) and the effect can be sudden destruction of the piece.

When the newer and thinner borosilicate glass containers first appeared on the market in the 1970s, they were sold with cork pads and the instructions were specific that they should be placed on the cork when removed from the heat - especially should not be placed on a ceramic tile surface (another heat sink) and the same goes for granite, etc., etc.

I don't care about all the technical jargon, I simply use common sense. Glass, ceramic and their relatives simply do not have the capacity to survive sudden temperature changes.

[Lisa Shock]

I broke an item this summer and replaced it, and now, I notice that the top edge has a green color, whereas my older items have a clear edge. Hope this helps!

[John Rosevear]

Does anyone know of a current-production brand of decent borosilicate kitchen glass? Clearly Pyrex is No Longer The Thing, at least in the US. Has anyone else stepped in? Alternatively, if the Euro Pyrex is still the good stuff, can anyone recommend a source that will ship to a US address for non-crazy money?

[thock]

Target has sold some borosilicate baking utensils from Green Apple, with a non-stick coating that is translucent. The coating is proprietary. I don't know whether Target still carries it, but I think you could search for it online.

[thock]

I too have many pieces of Pyrex, FireKing, Glasbake and other glass baking dishes as well as some stovetop glass pieces that have survived since the 1930s without breaking.

I never subject them to abrupt temperature changes because I know that is specifically forbidden.

The instructions that came with the original glass cooking vessels specified placing the hot dishes on a folded DRY towel. Good advice today.

If the casserole was removed from a hot oven and placed on the stovetop, I assume it was placed on the burner grid. That metal works as a heat sink (unless it has been pre-heated) and the effect can be sudden destruction of the piece.

When the newer and thinner borosilicate glass containers first appeared on the market in the 1970s, they were sold with cork pads and the instructions were specific that they should be placed on the cork when removed from the heat - especially should not be placed on a ceramic tile surface (another heat sink) and the same goes for granite, etc., etc.

I don't care about all the technical jargon, I simply use common sense. Glass, ceramic and their relatives simply do not have the capacity to survive sudden temperature changes.

Andie,

Do you put your borosilicate glassware in a pre-heated oven? I haven't been, because I'm concerned that it will crack. However, I do remember my mother putting Corningware and Pyrex in a pre-heated oven.

[baroness]

I'm not Andie, but I use my Pyrex and the like in a pre-heated oven. How else could one bake?

[prasantrin]

Pyrex can go from cold to hot--it can even go from freezer to a hot oven. It just can't go the other way around.

Other info from the Pyrex website (bolding is mine):

First, and most important, we want to assure all PYREX consumers that PYREX glass bakeware is and always has been safe to use when our Safety & Usage Instructions are followed. PYREX glass products are used in about 80 percent of U.S. homes and have maintained an excellent safety record for generations. Importantly, the Consumer Product Safety Commission, the federal agency charged with ensuring the safety of consumer products, has reviewed PYREX glass bakeware products and found no safety issue. There has never been a recall of PYREX glass bakeware.

It has been wrongly reported that World Kitchen is not a U.S. company, and that PYREX glass bakeware is now made in China. This is not true. PYREX glass products have been made in the U.S. since 1915. We continue to manufacture PYREX glass products in our Charleroi, Pennsylvania plant with union labor and our packaging displays the American flag and the "made in the USA" label.

It has also been wrongly suggested that World Kitchen lowered the quality of PYREX glass bakeware by switching from borosilicate glass to soda lime glass. Again, this is not true. The Charleroi plant has produced PYREX glass products out of a heat-strengthened (tempered) soda lime glass for about 60 years, first by our predecessor Corning Incorporated, and since 1998 by World Kitchen. In fact, since the 1980's, most, if not all consumer glass bakeware manufactured in the U.S. for consumers has been made of soda lime glass.

And their safety and usage instructions:

NEVER use on top of the stove, under a broiler, in a toaster oven, or place over oven vent or pilot light.

AVOID severe hot to cold temperature changes, including:

DO NOT add liquid to hot dish

DO NOT place hot dish or glass cover in sink

DO NOT immerse hot dish in water

DO NOT place hot dish on cold or wet surfaces

Handle hot ovenware and glass covers with dry potholders

ALWAYS add a small amount of liquid to the vessel prior to baking foods that release liquids while cooking.

DO NOT overheat oil or butter in microwave. Use minimum amount of cooking time.

DO NOT use or repair any item that is chipped, cracked or scratched.

CARE INSTRUCTIONS:

To loosen baked-on-food, allow glass to cool, then soak.

If scouring is necessary, use only plastic or nylon cleaning pads with nonabrasive cleansers.

Sometimes it pays to read manufacturers' instructions, even if they are "stoopid".

Edited November 14, 2009 by prasantrin (log)

[thock]

Thanks, all y'all. I had read the instructions (always do), but had heard some horror stories about people putting cold Pyrex in hot ovens and having it essentially disintegrate.

I STILL don't like the idea of non-borosilicate bakeware, but that's me.

[Darienne]

Consumer Reports this month (well, January 2011) has a very useful report on Pyrex: "Glass bakeware that shatters". There it is out in the open at last.

[emannths]

I once had a tempered glass shower door explode on me once. THAT was cool. The cracks instantly propagated though the pane, then it fell into the tub, where the little pieces continued to pop apart. It looked something like

, but more dramatic because it was in the freakin' shower. If you haven't experienced this, you're missing out on one of life's great thrills!

Anyway, my understanding is that when tempered glass breaks, it will shatter into these small little nuggets. Which makes it a pain to clean up, it also means that there are no sharp, jagged shards. So don't avoid it because you're worried that you're going to be sliced open by a baking dish.

[Darienne]

Anyway, my understanding is that when tempered glass breaks, it will shatter into these small little nuggets. Which makes it a pain to clean up, it also means that there are no sharp, jagged shards. So don't avoid it because you're worried that you're going to be sliced open by a baking dish.

On the contrary, although that is what the manufacturers claim, the Consumer Report article states that many of the dishes have indeed exploded into 'sharp shards that go flying'.

One consumer reported: 'Glass shards flew across the kitchen, including "multiple large glass fragments" and hundreds of "microscopic shards penetrated her face and eyes, causing serious injury and loss of vision"...'. p. 47, Consumer Reports, Jan 2011.

Scary as h*ll. Since I first learned about the change in glass composition in the Pyrex and other similar dishes, I have been buying old second hand pieces. Still you have to be careful with dishes which are scratched.

[andiesenji]

Andie,

Do you put your borosilicate glassware in a pre-heated oven? I haven't been, because I'm concerned that it will crack. However, I do remember my mother putting Corningware and Pyrex in a pre-heated oven.

Sorry, I missed this question last month.

I take Pyrex filled with stuff from the freezer, place it on a sheet pan and then into a pre-heated oven.

I do this routinely anyway, I simply don't put any vessel that is subject to breakage, whatever is in it, directly on an oven rack.

I don't do this to protect against heat shock but to prevent spill over and also because I once broke a pie plate when I stuck another pie plate in the oven a bit too forcefully.

I was not a happy camper cleaning up the debris from a pecan pie on the lower racks and on the floor of the oven and because some of the stuff had run through the holes in the sides I had to take that out and clean down around the burners.

As I said in my earlier post. I have glass baking dishes as well as stove top vessels that were made in the first half of the last century and they still function just fine.

I have an instruction card that was in a box with a Pyrex "Flameware" double boiler and it stresses that after removing from the stove top only place the hot pot on a folded towel, a wooden trivet or a cork hot pad. It specifically warned against setting the hot pot on an enamel counter or table top (common in those days), onto a tiled surface or into the sink, with or without water.

Frankly, I don't like the newer Pyrex made from soda glass. I think it scratches easier. I have one Pyrex 10 inch pie plate with the earliest Pyrex round logs on the bottom (dates it to 1919-1932) which has fewer scratches than some I purchased in the early '90s and it has been in constant use.

As a matter of fact, I just published a page about glass cookware and bakeware on my blog this morning and a photo of that pie plate is the first one on the page.

My blog page on this subject.

Edited December 9, 2010 by andiesenji (log)

[thock]

It was a year ago, last month, but that's ok.

Thanks for the info and the link to your blog post. I'll have to read it later. The spill prevention idea is a good one, and one I'll have to adopt because I'm a big klutz.

I agree that the newer stuff seems to scratch more easily. I have been picking up old(er) Pyrex at thrift stores and yard sales, but sometimes it's hard to determine what's "old enough." I've pretty much narrowed down that if it has the all-smalls "pyrex" on it, it's not old enough. But some of the all-caps PYREX might not be, either.

I wish shipping from Europe was cheaper. <sigh>

ETA: Do you happen to have a list of the marks and what years they were used somewhere on your blog?

Edited December 9, 2010 by thock (log)

[Dakki]

Collecting vintage glass bakeware is pretty hardcore.

I have a load of the stuff that I liberated from my mother. It was supposedly some of her wedding presents so that would date it to the early or mid 70s. Is this the good glass or no?

[andiesenji]

It was a year ago, last month, but that's ok.

Thanks for the info and the link to your blog post. I'll have to read it later. The spill prevention idea is a good one, and one I'll have to adopt because I'm a big klutz.

I agree that the newer stuff seems to scratch more easily. I have been picking up old(er) Pyrex at thrift stores and yard sales, but sometimes it's hard to determine what's "old enough." I've pretty much narrowed down that if it has the all-smalls "pyrex" on it, it's not old enough. But some of the all-caps PYREX might not be, either.

I wish shipping from Europe was cheaper. <sigh>

ETA: Do you happen to have a list of the marks and what years they were used somewhere on your blog?

The earliest Pyrex marks had a small circle with PYREX in all caps and with dollar signs above and below the R and around the top and bottom of the circle U.S. Reg. Pat.Off. No patent number yet.

Later pieces had pyrex in small case in a circle with a patent number and the logos have varied slightly over the years.

The early stove top stuff always had the flame logo and "Flameware" in the backstamp name.

Some history sources date the change over from borosilicate glass to soda-lime glass at Pyrex to 1988 and some to 1990 when the cooking products division was changed to World Kitchen.

Pyrex still manufactures laboratory glass using the same borosilicate formula that has been used for many decades.

Edited December 9, 2010 by andiesenji (log)

[thock]

Oh thanks! I have a selection of Pyrex and other brands of glassware. Here are some of them. Your post helped me to determine that some of them might be quite old.

The two lower ones in this photo are small, maybe 6" diameter. The one on the left says T.M. REG, but no numberThe one on the right is a Glasbake which says U.S.A. 464 (?) on the top and bottom. The upper right-hand one is one that has the PYREX in a circle with T.M. REG U.S. PAT. OFF. and 603 and B-N. No dollar signs, though. The upper left one has PYREX with the registered trademark symbol, 209 9 INCH, TRADE MARK, BB-9 above the PYREX, and below, MADE IN U.S.A., FOR OVEN BAKING ONLY.

The upper-left ones in this photo are deep casseroles, I think, 2 qt. Anchor Hocking Fire-King ovenware. The upper right one says PYREX in an ellipse with "de CORNING" under it on one handle, and on the other, FRANCE in another ellipse.

The loaf pan is a Fire-King 1 qt with T.M. REG. and MADE IN U.S.A. on it.

The oval casserole has PYREX CORNING NY USA on it. The rectangular pan has T.M. REG., PYREX, U.S. PAT. OFF in a circle, and one of the handles is chipped.

Thank you!

[Darienne]

October 2011 Consumer Reports update on glass measuring cups, bowls and baking dishes with the rather distressing title "Shattered Glass". It appears that the manufacturers, such as Pyrex and Anchor Hocking, are still blaming consumer misuse of the products upon all accidents.

[Katie Meadow]

I have my share of hardware store Pyrex: pie dish, standard 8 x 8 and 9 x 12, a loaf pan, measuring cups etc. Everything is at least 15 to possibly 40 years old. Two weeks ago we were having dinner and heard a scary noise. My trusty 2-qt pyrex measuring cup that was sitting quietly on its shelf simply cracked into three pieces with no help from anyone. There were no previously visible cracks or flaws in it that I'd noticed. This got heavy use, primarily as a mixing bowl. It was typically hand washed, drain dried and put away. I certainly hadn't used it any differently recently than I have in the last two decades. Poltergeists? I bought a new one; we'll see how long it lasts.

[Darienne]

I have my share of hardware store Pyrex: pie dish, standard 8 x 8 and 9 x 12, a loaf pan, measuring cups etc. Everything is at least 15 to possibly 40 years old. Two weeks ago we were having dinner and heard a scary noise. My trusty 2-qt pyrex measuring cup that was sitting quietly on its shelf simply cracked into three pieces with no help from anyone. There were no previously visible cracks or flaws in it that I'd noticed. This got heavy use, primarily as a mixing bowl. It was typically hand washed, drain dried and put away. I certainly hadn't used it any differently recently than I have in the last two decades. Poltergeists? I bought a new one; we'll see how long it lasts.

Very distressing. Gave me the early morning willies.

I would assume that the new one will not have any useful qualities of the older ones. If you read the Consumer Report issues, this current one and the earlier one, Jan 2011, you will get quite an insight into the situation.

Re-quoting from my earlier post from that Jan issue: 'Glass shards flew across the kitchen, including "multiple large glass fragments" and hundreds of "microscopic shards penetrated her face and eyes, causing serious injury and loss of vision"...'. p. 47

Aarrgghhh.

[mgaretz]

I haven't broken a clear glass item yet, but I have been in the kitchen when a Corelle item has broken (essentially the same tempered glass). They explode into thousands of tiny shards and few bigger pieces. The shards are needle sharp and go everywhere. So when one breaks it's a mess. The upside is that they are very durable, so I still use them.

[Lisa Shock]

I would like to mention that Duralex glassware is still tempered glass of high quality. I have manged to get some so-called 'used' Picardie items on amazon that were customer returns with damaged packaging but brand-new, unused merchandise at big discounts.